diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 93599e8..960d5c8 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -491,4 +491,132 @@ mod p1706_where_will_the_ball_fall;
 
 mod p1299_replace_elements_with_greatest_element_on_right_side;
 
+mod p2080_range_frequency_queries;
+
+mod p624_maximum_distance_in_arrays;
+
+mod p2595_number_of_even_and_odd_bits;
+
+mod p2209_minimum_white_tiles_after_covering_with_carpets;
+
+mod p2506_count_pairs_of_similar_strings;
+
+mod p1206_design_skiplist;
+
+mod p1656_design_an_ordered_stream;
+
+mod p2502_design_memory_allocator;
+
+mod p1472_design_browser_history;
+
+mod p2353_design_a_food_rating_system;
+
+mod p131_palindrome_partitioning;
+
+mod p132_palindrome_partitioning_ii;
+
+mod p1278_palindrome_partitioning_iii;
+
+mod p1745_palindrome_partitioning_iv;
+
+mod p1328_break_a_palindrome;
+
+mod p2588_count_the_number_of_beautiful_subarrays;
+
+mod p2597_the_number_of_beautiful_subsets;
+
+mod p2234_maximum_total_beauty_of_the_gardens;
+
+mod p2070_most_beautiful_item_for_each_query;
+
+mod p2269_find_the_k_beauty_of_a_number;
+
+mod p2012_sum_of_beauty_in_the_array;
+
+mod p3305_count_of_substrings_containing_every_vowel_and_k_consonants_i;
+
+mod p3306_count_of_substrings_containing_every_vowel_and_k_consonants_ii;
+
+mod p3340_check_balanced_string;
+
+mod p3110_score_of_a_string;
+
+mod p2272_substring_with_largest_variance;
+
+mod p1963_minimum_number_of_swaps_to_make_the_string_balanced;
+
+mod p2614_prime_in_diagonal;
+
+mod p2610_convert_an_array_into_a_2d_array_with_conditions;
+
+mod p2612_minimum_reverse_operations;
+
+mod p2680_maximum_or;
+
+mod p2643_row_with_maximum_ones;
+
+mod p2116_check_if_a_parentheses_string_can_be_valid;
+
+mod p2255_count_prefixes_of_a_given_string;
+
+mod p2711_difference_of_number_of_distinct_values_on_diagonals;
+
+mod p2829_determine_the_minimum_sum_of_a_k_avoiding_array;
+
+mod p2712_minimum_cost_to_make_all_characters_equal;
+
+mod p2716_minimize_string_length;
+
+mod p2360_longest_cycle_in_a_graph;
+
+mod p2109_adding_spaces_to_a_string;
+
+mod p2278_percentage_of_letter_in_string;
+
+mod p2140_solving_questions_with_brainpower;
+
+mod p2873_maximum_value_of_an_ordered_triplet_i;
+
+mod p2874_maximum_value_of_an_ordered_triplet_ii;
+
+mod p1123_lowest_common_ancestor_of_deepest_leaves;
+
+mod p1863_sum_of_all_subset_xor_totals;
+
+mod p368_largest_divisible_subset;
+
+mod p416_partition_equal_subset_sum;
+
+mod p3396_minimum_number_of_operations_to_make_elements_in_array_distinct;
+
+mod p2999_count_the_number_of_powerful_integers;
+mod p3375_minimum_operations_to_make_array_values_equal_to_k;
+
+mod p2843_count_symmetric_integers;
+
+mod p3272_find_the_count_of_good_integers;
+
+mod p1922_count_good_numbers;
+
+mod p1534_count_good_triplets;
+
+mod p2179_count_good_triplets_in_an_array;
+
+mod p2537_count_the_number_of_good_subarrays;
+
+mod p2176_count_equal_and_divisible_pairs_in_an_array;
+
+mod p2364_count_number_of_bad_pairs;
+
+mod p2563_count_the_number_of_fair_pairs;
+
+mod p781_rabbits_in_forest;
+
+mod p2145_count_the_hidden_sequences;
+
+mod p1399_count_largest_group;
+mod p2338_count_the_number_of_ideal_arrays;
+
+mod p2845_count_of_interesting_subarrays;
+
 mod p1287_element_appearing_more_than_25_in_sorted_array;
\ No newline at end of file
diff --git a/src/problem/p1123_lowest_common_ancestor_of_deepest_leaves.rs b/src/problem/p1123_lowest_common_ancestor_of_deepest_leaves.rs
new file mode 100644
index 0000000..17d2921
--- /dev/null
+++ b/src/problem/p1123_lowest_common_ancestor_of_deepest_leaves.rs
@@ -0,0 +1,98 @@
+/**
+ * [1123] Lowest Common Ancestor of Deepest Leaves
+ */
+pub struct Solution {}
+
+use crate::util::tree::{to_tree, TreeNode};
+
+// submission codes start here
+
+// Definition for a binary tree node.
+// #[derive(Debug, PartialEq, Eq)]
+// pub struct TreeNode {
+//   pub val: i32,
+//   pub left: Option<Rc<RefCell<TreeNode>>>,
+//   pub right: Option<Rc<RefCell<TreeNode>>>,
+// }
+//
+// impl TreeNode {
+//   #[inline]
+//   pub fn new(val: i32) -> Self {
+//     TreeNode {
+//       val,
+//       left: None,
+//       right: None
+//     }
+//   }
+// }
+use std::cell::RefCell;
+use std::cmp::Ordering;
+use std::rc::Rc;
+
+impl Solution {
+    pub fn lca_deepest_leaves(
+        root: Option<Rc<RefCell<TreeNode>>>,
+    ) -> Option<Rc<RefCell<TreeNode>>> {
+        if let Some(root) = root {
+            Self::search(&root).1
+        } else {
+            None
+        }
+    }
+
+    // (子树的深度，lca）
+    fn search(node: &Rc<RefCell<TreeNode>>) -> (i32, Option<Rc<RefCell<TreeNode>>>) {
+        let (left_deep, left_lca) = if let Some(left) = node.borrow().left.as_ref() {
+            Self::search(left)
+        } else {
+            (0, None)
+        };
+
+        let (right_deep, right_lca) = if let Some(right) = node.borrow().right.as_ref() {
+            Self::search(right)
+        } else {
+            (0, None)
+        };
+
+        match left_deep.cmp(&right_deep) {
+            Ordering::Greater => (left_deep + 1, left_lca),
+            Ordering::Less => (right_deep + 1, right_lca),
+            Ordering::Equal => (left_deep + 1, Some(node.clone())),
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1123() {
+        let node = Solution::lca_deepest_leaves(to_tree(vec![
+            Some(3),
+            Some(5),
+            Some(1),
+            Some(6),
+            Some(2),
+            Some(0),
+            Some(8),
+            None,
+            None,
+            Some(7),
+            Some(4),
+        ]));
+
+        assert_eq!(to_tree(vec![Some(2), Some(7), Some(4)]), node);
+
+        assert_eq!(
+            to_tree(vec![Some(1)]),
+            Solution::lca_deepest_leaves(to_tree(vec![Some(1)]))
+        );
+        assert_eq!(
+            to_tree(vec![Some(2)]),
+            Solution::lca_deepest_leaves(to_tree(vec![Some(0), Some(1), Some(3), None, Some(2)]))
+        );
+    }
+}
diff --git a/src/problem/p1206_design_skiplist.rs b/src/problem/p1206_design_skiplist.rs
new file mode 100644
index 0000000..ff35cf4
--- /dev/null
+++ b/src/problem/p1206_design_skiplist.rs
@@ -0,0 +1,189 @@
+/**
+ * [1206] Design Skiplist
+ */
+pub struct Solution {}
+
+// submission codes start here
+use rand::Rng;
+use std::cell::RefCell;
+use std::rc::Rc;
+
+struct SkiplistNode {
+    right: Option<Rc<RefCell<SkiplistNode>>>,
+    down: Option<Rc<RefCell<SkiplistNode>>>,
+    value: i32,
+}
+
+type NodeCell = Rc<RefCell<SkiplistNode>>;
+
+struct Skiplist {
+    head: Rc<RefCell<SkiplistNode>>,
+    random_engine: rand::rngs::ThreadRng,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl Skiplist {
+    fn create_node(value: i32) -> NodeCell {
+        Rc::new(RefCell::new(SkiplistNode {
+            right: None,
+            down: None,
+            value,
+        }))
+    }
+
+    fn new() -> Self {
+        Self {
+            head: Self::create_node(-1),
+            random_engine: rand::thread_rng(),
+        }
+    }
+
+    fn search(&self, target: i32) -> bool {
+        let mut node = Some(self.head.clone());
+        let mut queue = vec![];
+
+        while let Some(real_node) = node {
+            node = if real_node
+                .borrow()
+                .right
+                .clone()
+                .filter(|x| x.borrow().value <= target)
+                .is_some()
+            {
+                real_node.borrow().right.clone()
+            } else {
+                queue.push(real_node.clone());
+                real_node.borrow().down.clone()
+            };
+        }
+
+        queue
+            .last()
+            .filter(|x| x.borrow().value == target)
+            .is_some()
+    }
+
+    fn add(&mut self, num: i32) {
+        let mut path = vec![];
+        let mut node = Some(self.head.clone());
+
+        // 找链表中所有小于num的节点
+        while let Some(real_node) = node {
+            node = if real_node
+                .borrow()
+                .right
+                .as_ref()
+                .filter(|x| x.borrow().value <= num)
+                .is_some()
+            {
+                real_node.borrow().right.clone()
+            } else {
+                path.push(real_node.clone());
+                real_node.borrow().down.as_ref().map(|x| x.clone())
+            };
+        }
+
+        let mut insert = true;
+        let mut down_node = None;
+
+        while insert && !path.is_empty() {
+            if let Some(insert_node) = path.pop() {
+                // 添加新的节点
+                let right_node = insert_node.borrow_mut().right.take();
+                insert_node.borrow_mut().right = Some(Rc::new(RefCell::new(SkiplistNode {
+                    right: right_node,
+                    down: down_node.take(),
+                    value: num,
+                })));
+
+                down_node = insert_node.borrow().right.as_ref().map(|x| x.clone());
+                // 50%的概率决定是否添加下一级索引
+                insert = self.random_engine.gen_bool(0.5);
+            } else {
+                break;
+            }
+        }
+
+        // 新增头结点
+        // 这里新增一层
+        if insert {
+            let node = Skiplist::create_node(-1);
+            node.borrow_mut().down = Some(self.head.clone());
+            self.head = node;
+        }
+    }
+
+    fn erase(&self, num: i32) -> bool {
+        let mut deleted = false;
+        let mut node = Some(self.head.clone());
+
+        while let Some(mut real_node) = node {
+            node = if real_node
+                .borrow()
+                .right
+                .as_ref()
+                .filter(|x| x.borrow().value < num)
+                .is_some()
+            {
+                real_node.borrow().right.clone()
+            } else {
+                real_node.borrow().down.clone()
+            };
+
+            if real_node
+                .borrow()
+                .right
+                .as_ref()
+                .filter(|x| x.borrow().value == num)
+                .is_some()
+            {
+                deleted = true;
+                let right = real_node
+                    .borrow_mut()
+                    .right
+                    .as_ref()
+                    .unwrap()
+                    .borrow()
+                    .right
+                    .as_ref()
+                    .map(|x| x.clone());
+                real_node.borrow_mut().right = right;
+            }
+        }
+
+        deleted
+    }
+}
+
+/**
+ * Your Skiplist object will be instantiated and called as such:
+ * let obj = Skiplist::new();
+ * let ret_1: bool = obj.search(target);
+ * obj.add(num);
+ * let ret_3: bool = obj.erase(num);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1206() {
+        let mut list = Skiplist::new();
+
+        list.add(1);
+        list.add(2);
+        list.add(3);
+        assert!(!list.search(0));
+        list.add(4);
+        assert!(list.search(1));
+        assert!(!list.erase(0));
+        assert!(list.erase(1));
+        assert!(!list.search(1));
+    }
+}
diff --git a/src/problem/p1278_palindrome_partitioning_iii.rs b/src/problem/p1278_palindrome_partitioning_iii.rs
new file mode 100644
index 0000000..acf7ada
--- /dev/null
+++ b/src/problem/p1278_palindrome_partitioning_iii.rs
@@ -0,0 +1,60 @@
+/**
+ * [1278] Palindrome Partitioning III
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn palindrome_partition(s: String, k: i32) -> i32 {
+        let s: Vec<char> = s.chars().collect();
+        let length = s.len();
+
+        // cost[i][j]
+        // 将 s[i..=j] 修改为回文串需要的修改次数
+        let mut cost = vec![vec![0; length]; length];
+
+        for span in 2..=length {
+            for i in 0..=length - span {
+                let j = i + span - 1;
+
+                cost[i][j] = cost[i + 1][j - 1] + if s[i] == s[j] { 0 } else { 1 };
+            }
+        }
+
+        let k = k as usize;
+        // dp[i][j]
+        // 将s[..i]分割为j个回文串需要的修改次数
+        let mut dp = vec![vec![i32::MAX; k + 1]; length + 1];
+
+        for i in 1..=length {
+            for j in 1..=i.min(k) {
+                if j == 1 {
+                    dp[i][j] = cost[0][i - 1];
+                } else {
+                    // 这里k从j - 1开始枚举是因为前面需要进行j - 1次分割时
+                    // 字符串的长度必须大于等于j - 1
+                    for k in j - 1..i {
+                        dp[i][j] = dp[i][j].min(dp[k][j - 1] + cost[k][i - 1]);
+                    }
+                }
+            }
+        }
+
+        dp[length][k]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1278() {
+        assert_eq!(1, Solution::palindrome_partition("abc".to_owned(), 2));
+        assert_eq!(0, Solution::palindrome_partition("aabbc".to_owned(), 3));
+        assert_eq!(0, Solution::palindrome_partition("leetcode".to_owned(), 8));
+    }
+}
diff --git a/src/problem/p131_palindrome_partitioning.rs b/src/problem/p131_palindrome_partitioning.rs
new file mode 100644
index 0000000..d782026
--- /dev/null
+++ b/src/problem/p131_palindrome_partitioning.rs
@@ -0,0 +1,63 @@
+/**
+ * [131] Palindrome Partitioning
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn partition(s: String) -> Vec<Vec<String>> {
+        let s: Vec<char> = s.chars().collect();
+        let length = s.len();
+
+        let mut result = vec![];
+        let mut current: Vec<String> = vec![];
+        let mut dp = vec![vec![true; length]; length];
+
+        for i in (0..length).rev() {
+            for j in i + 1..length {
+                dp[i][j] = (s[i] == s[j]) && dp[i + 1][j - 1];
+            }
+        }
+
+        Self::dfs(&s, 0, &mut dp, &mut current, &mut result);
+
+        result
+    }
+
+    fn dfs(
+        s: &Vec<char>,
+        pos: usize,
+        dp: &mut Vec<Vec<bool>>,
+        current: &mut Vec<String>,
+        result: &mut Vec<Vec<String>>,
+    ) {
+        if pos >= s.len() {
+            result.push(current.clone());
+            return;
+        }
+
+        for i in pos..s.len() {
+            if dp[pos][i] {
+                current.push(s[pos..i + 1].iter().collect());
+                Self::dfs(s, i + 1, dp, current, result);
+                current.pop();
+            }
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_131() {
+        assert_eq!(
+            vec![vec_string!("a", "a", "b"), vec_string!("aa", "b")],
+            Solution::partition("aab".to_owned())
+        );
+    }
+}
diff --git a/src/problem/p1328_break_a_palindrome.rs b/src/problem/p1328_break_a_palindrome.rs
new file mode 100644
index 0000000..f78f3a6
--- /dev/null
+++ b/src/problem/p1328_break_a_palindrome.rs
@@ -0,0 +1,50 @@
+/**
+ * [1328] Break a Palindrome
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn break_palindrome(palindrome: String) -> String {
+        if palindrome.len() == 1 {
+            return "".to_owned();
+        }
+
+        let mut s: Vec<char> = palindrome.chars().collect();
+
+        let mut flag = false;
+        for i in 0..s.len() / 2 {
+            if s[i] != 'a' {
+                s[i] = 'a';
+                flag = true;
+                break;
+            }
+        }
+
+        // 说明s的前半段全部都是a
+        // 直接把最后一个字符改成b
+        if !flag {
+            let pos = s.len() - 1;
+            s[pos] = 'b';
+        }
+
+        s.into_iter().collect()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1328() {
+        assert_eq!("aabab", Solution::break_palindrome("aabaa".to_owned()));
+        assert_eq!("ab", Solution::break_palindrome("aa".to_owned()));
+        assert_eq!("ab", Solution::break_palindrome("bb".to_owned()));
+        assert_eq!("aaccba", Solution::break_palindrome("abccba".to_owned()));
+        assert_eq!("", Solution::break_palindrome("a".to_owned()));
+    }
+}
diff --git a/src/problem/p132_palindrome_partitioning_ii.rs b/src/problem/p132_palindrome_partitioning_ii.rs
new file mode 100644
index 0000000..1e7ba50
--- /dev/null
+++ b/src/problem/p132_palindrome_partitioning_ii.rs
@@ -0,0 +1,51 @@
+/**
+ * [132] Palindrome Partitioning II
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn min_cut(s: String) -> i32 {
+        let s: Vec<char> = s.chars().collect();
+        let length = s.len();
+
+        let mut palindorme = vec![vec![true; length]; length];
+
+        for i in (0..length).rev() {
+            for j in i + 1..length {
+                palindorme[i][j] = (s[i] == s[j]) && palindorme[i + 1][j - 1]
+            }
+        }
+
+        let mut dp = vec![i32::MAX; length];
+
+        for i in 0..length {
+            if palindorme[0][i] {
+                dp[i] = 0;
+            } else {
+                for j in 0..i {
+                    if palindorme[j + 1][i] {
+                        dp[i] = dp[i].min(dp[j] + 1);
+                    }
+                }
+            }
+        }
+
+        dp[length - 1]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_132() {
+        assert_eq!(1, Solution::min_cut("aab".to_owned()));
+        assert_eq!(0, Solution::min_cut("a".to_owned()));
+        assert_eq!(1, Solution::min_cut("ab".to_owned()));
+    }
+}
diff --git a/src/problem/p1399_count_largest_group.rs b/src/problem/p1399_count_largest_group.rs
new file mode 100644
index 0000000..d5e5573
--- /dev/null
+++ b/src/problem/p1399_count_largest_group.rs
@@ -0,0 +1,49 @@
+/**
+ * [1399] Count Largest Group
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn count_largest_group(n: i32) -> i32 {
+        let mut map = HashMap::new();
+        (1..=n)
+            .into_iter()
+            .map(|mut x| {
+                let mut result = 0;
+
+                while x > 0 {
+                    result += x % 10;
+                    x = x / 10;
+                }
+
+                result
+            })
+            .fold(&mut map, |map, i| {
+                let entry = map.entry(i).or_insert(0);
+                *entry += 1;
+
+                map
+            });
+
+        let max_count = map.values().max().unwrap();
+        map.values().filter(|x| x == &max_count).count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1399() {
+        assert_eq!(4, Solution::count_largest_group(13));
+        assert_eq!(2, Solution::count_largest_group(2));
+        assert_eq!(6, Solution::count_largest_group(15));
+        assert_eq!(5, Solution::count_largest_group(24));
+    }
+}
diff --git a/src/problem/p1472_design_browser_history.rs b/src/problem/p1472_design_browser_history.rs
new file mode 100644
index 0000000..b8d09a5
--- /dev/null
+++ b/src/problem/p1472_design_browser_history.rs
@@ -0,0 +1,87 @@
+/**
+ * [1472] Design Browser History
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+struct BrowserHistory {
+    history: Vec<String>,
+    pos: usize,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl BrowserHistory {
+    fn new(homepage: String) -> Self {
+        Self {
+            history: vec![homepage],
+            pos: 0,
+        }
+    }
+
+    fn visit(&mut self, url: String) {
+        // 删除前向的所有网站
+        for _ in self.pos + 1..self.history.len() {
+            self.history.pop();
+        }
+
+        self.history.push(url);
+        self.pos += 1;
+    }
+
+    fn back(&mut self, steps: i32) -> String {
+        let steps = steps as usize;
+        if steps > self.pos {
+            self.pos = 0;
+        } else {
+            self.pos -= steps;
+        }
+
+        self.history[self.pos].clone()
+    }
+
+    fn forward(&mut self, steps: i32) -> String {
+        let steps = steps as usize;
+        if steps + self.pos >= self.history.len() {
+            self.pos = self.history.len() - 1;
+        } else {
+            self.pos += steps;
+        }
+
+        self.history[self.pos].clone()
+    }
+}
+
+/**
+ * Your BrowserHistory object will be instantiated and called as such:
+ * let obj = BrowserHistory::new(homepage);
+ * obj.visit(url);
+ * let ret_2: String = obj.back(steps);
+ * let ret_3: String = obj.forward(steps);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1472() {
+        let mut history = BrowserHistory::new("leetcode.com".to_owned());
+
+        history.visit("google.com".to_owned());
+        history.visit("facebook.com".to_owned());
+        history.visit("youtube.com".to_owned());
+        assert_eq!("facebook.com", history.back(1));
+        assert_eq!("google.com", history.back(1));
+        assert_eq!("facebook.com", history.forward(1));
+        history.visit("linkedin.com".to_owned());
+        assert_eq!("linkedin.com", history.forward(2));
+        assert_eq!("google.com", history.back(2));
+        assert_eq!("leetcode.com", history.back(7));
+    }
+}
diff --git a/src/problem/p1534_count_good_triplets.rs b/src/problem/p1534_count_good_triplets.rs
new file mode 100644
index 0000000..2d02d72
--- /dev/null
+++ b/src/problem/p1534_count_good_triplets.rs
@@ -0,0 +1,54 @@
+/**
+ * [1534] Count Good Triplets
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_good_triplets(arr: Vec<i32>, a: i32, b: i32, c: i32) -> i32 {
+        let mut result = 0;
+        let (a, b, c) = (a as u32, b as u32, c as u32);
+
+        for i in 0..arr.len() {
+            for j in i + 1..arr.len() {
+                for k in j + 1..arr.len() {
+                    if arr[i].abs_diff(arr[j]) > a {
+                        continue;
+                    }
+
+                    if arr[j].abs_diff(arr[k]) > b {
+                        continue;
+                    }
+
+                    if arr[i].abs_diff(arr[k]) > c {
+                        continue;
+                    }
+
+                    result += 1;
+                }
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1534() {
+        assert_eq!(
+            4,
+            Solution::count_good_triplets(vec![3, 0, 1, 1, 9, 7], 7, 2, 3)
+        );
+        assert_eq!(
+            0,
+            Solution::count_good_triplets(vec![1, 1, 2, 2, 3], 0, 0, 1)
+        );
+    }
+}
diff --git a/src/problem/p1656_design_an_ordered_stream.rs b/src/problem/p1656_design_an_ordered_stream.rs
new file mode 100644
index 0000000..8b0c350
--- /dev/null
+++ b/src/problem/p1656_design_an_ordered_stream.rs
@@ -0,0 +1,71 @@
+/**
+ * [1656] Design an Ordered Stream
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+struct OrderedStream {
+    array: Vec<Option<String>>,
+    pointer: usize,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl OrderedStream {
+    fn new(n: i32) -> Self {
+        let n = n as usize;
+
+        Self {
+            array: vec![None; n],
+            pointer: 1,
+        }
+    }
+
+    fn insert(&mut self, id_key: i32, value: String) -> Vec<String> {
+        let id = id_key as usize - 1;
+
+        self.array[id] = Some(value);
+
+        let mut result = vec![];
+        let mut pointer = self.pointer;
+
+        while pointer <= self.array.len() {
+            if let Some(item) = &self.array[pointer - 1] {
+                result.push(item.clone());
+                pointer += 1;
+            } else {
+                break;
+            }
+        }
+        self.pointer = pointer;
+
+        result
+    }
+}
+
+/**
+ * Your OrderedStream object will be instantiated and called as such:
+ * let obj = OrderedStream::new(n);
+ * let ret_1: Vec<String> = obj.insert(idKey, value);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1656() {
+        let mut stream = OrderedStream::new(5);
+
+        assert_eq!(Vec::<&str>::new(), stream.insert(3, "ccccc".to_owned()));
+        assert_eq!(vec!["aaaaa"], stream.insert(1, "aaaaa".to_owned()));
+        assert_eq!(vec!["bbbbb", "ccccc"], stream.insert(2, "bbbbb".to_owned()));
+        assert_eq!(Vec::<&str>::new(), stream.insert(5, "eeeee".to_owned()));
+        assert_eq!(vec!["ddddd", "eeeee"], stream.insert(4, "ddddd".to_owned()));
+    }
+}
diff --git a/src/problem/p1745_palindrome_partitioning_iv.rs b/src/problem/p1745_palindrome_partitioning_iv.rs
new file mode 100644
index 0000000..c2abb55
--- /dev/null
+++ b/src/problem/p1745_palindrome_partitioning_iv.rs
@@ -0,0 +1,46 @@
+/**
+ * [1745] Palindrome Partitioning IV
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn check_partitioning(s: String) -> bool {
+        let s = s.as_bytes();
+        let length = s.len();
+
+        let mut palindrome = vec![vec![true; length]; length];
+
+        for span in 2..=length {
+            for i in 0..=length - span {
+                let j = i + span - 1;
+                palindrome[i][j] = palindrome[i + 1][j - 1] && (s[i] == s[j])
+            }
+        }
+
+        for i in 0..length - 2 {
+            // 所有字符串都必须是非空的
+            for j in i + 2..length {
+                if palindrome[0][i] && palindrome[i + 1][j - 1] && palindrome[j][length - 1] {
+                    return true;
+                }
+            }
+        }
+
+        false
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1745() {
+        assert!(Solution::check_partitioning("abcbdd".to_owned()));
+        assert!(!Solution::check_partitioning("bcbddxy".to_owned()));
+    }
+}
diff --git a/src/problem/p1863_sum_of_all_subset_xor_totals.rs b/src/problem/p1863_sum_of_all_subset_xor_totals.rs
new file mode 100644
index 0000000..cae7070
--- /dev/null
+++ b/src/problem/p1863_sum_of_all_subset_xor_totals.rs
@@ -0,0 +1,43 @@
+/**
+ * [1863] Sum of All Subset XOR Totals
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn subset_xor_sum(nums: Vec<i32>) -> i32 {
+        let mut result = 0;
+
+        Self::search(0, 0, &nums, &mut result);
+
+        result
+    }
+
+    fn search(mut sum: i32, i: usize, nums: &Vec<i32>, result: &mut i32) {
+        if i == nums.len() {
+            return;
+        }
+
+        // 不选择i
+        Self::search(sum, i + 1, nums, result);
+        // 选择i
+        sum = sum ^ nums[i];
+        *result += sum;
+        Self::search(sum, i + 1, nums, result);
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1863() {
+        assert_eq!(6, Solution::subset_xor_sum(vec![1, 3]));
+        assert_eq!(28, Solution::subset_xor_sum(vec![5, 1, 6]));
+        assert_eq!(480, Solution::subset_xor_sum(vec![3, 4, 5, 6, 7, 8]));
+    }
+}
diff --git a/src/problem/p1922_count_good_numbers.rs b/src/problem/p1922_count_good_numbers.rs
new file mode 100644
index 0000000..b629939
--- /dev/null
+++ b/src/problem/p1922_count_good_numbers.rs
@@ -0,0 +1,49 @@
+/**
+ * [1922] Count Good Numbers
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+const MOD: i64 = 1_000_000_000 + 7;
+
+impl Solution {
+    pub fn count_good_numbers(n: i64) -> i32 {
+        let mut result = Self::quick_power(20, n / 2);
+
+        if n % 2 == 1 {
+            result = result * 5 % MOD;
+        }
+
+        result as i32
+    }
+
+    fn quick_power(mut m: i64, mut n: i64) -> i64 {
+        let mut result = 1;
+
+        while n > 0 {
+            if n & 1 == 1 {
+                result = result * m % MOD;
+            }
+
+            m = m * m % MOD;
+            n = n >> 1;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1922() {
+        assert_eq!(5, Solution::count_good_numbers(1));
+        assert_eq!(400, Solution::count_good_numbers(4));
+        assert_eq!(564_908_303, Solution::count_good_numbers(50));
+    }
+}
diff --git a/src/problem/p1963_minimum_number_of_swaps_to_make_the_string_balanced.rs b/src/problem/p1963_minimum_number_of_swaps_to_make_the_string_balanced.rs
new file mode 100644
index 0000000..e3bc98d
--- /dev/null
+++ b/src/problem/p1963_minimum_number_of_swaps_to_make_the_string_balanced.rs
@@ -0,0 +1,40 @@
+/**
+ * [1963] Minimum Number of Swaps to Make the String Balanced
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn min_swaps(s: String) -> i32 {
+        let mut count = 0;
+        let mut min_count = 0;
+
+        for c in s.chars() {
+            match c {
+                '[' => count += 1,
+                ']' => {
+                    count -= 1;
+                    min_count = min_count.min(count)
+                }
+                _ => {}
+            }
+        }
+
+        (-min_count + 1) / 2
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1963() {
+        assert_eq!(1, Solution::min_swaps("][][".to_owned()));
+        assert_eq!(2, Solution::min_swaps("]]][[[".to_owned()));
+        assert_eq!(0, Solution::min_swaps("[]".to_owned()));
+    }
+}
diff --git a/src/problem/p2012_sum_of_beauty_in_the_array.rs b/src/problem/p2012_sum_of_beauty_in_the_array.rs
new file mode 100644
index 0000000..3634a0b
--- /dev/null
+++ b/src/problem/p2012_sum_of_beauty_in_the_array.rs
@@ -0,0 +1,48 @@
+/**
+ * [2012] Sum of Beauty in the Array
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn sum_of_beauties(nums: Vec<i32>) -> i32 {
+        let n = nums.len();
+        let mut prefix = vec![0; n];
+        let mut suffix = vec![i32::MAX; n];
+
+        for i in 0..n {
+            if i > 0 {
+                prefix[i] = prefix[i - 1].max(nums[i - 1]);
+                suffix[n - i - 1] = suffix[n - i].min(nums[n - i]);
+            }
+        }
+
+        (1..n - 1)
+            .into_iter()
+            .map(|x| {
+                if nums[x] > prefix[x] && nums[x] < suffix[x] {
+                    2
+                } else if nums[x] > nums[x - 1] && nums[x] < nums[x + 1] {
+                    1
+                } else {
+                    0
+                }
+            })
+            .sum()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2012() {
+        assert_eq!(1, Solution::sum_of_beauties(vec![2, 4, 6, 4]));
+        assert_eq!(2, Solution::sum_of_beauties(vec![1, 2, 3]));
+        assert_eq!(0, Solution::sum_of_beauties(vec![3, 2, 1]));
+    }
+}
diff --git a/src/problem/p2070_most_beautiful_item_for_each_query.rs b/src/problem/p2070_most_beautiful_item_for_each_query.rs
new file mode 100644
index 0000000..5f4d777
--- /dev/null
+++ b/src/problem/p2070_most_beautiful_item_for_each_query.rs
@@ -0,0 +1,72 @@
+/**
+ * [2070] Most Beautiful Item for Each Query
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::BTreeMap;
+
+impl Solution {
+    pub fn maximum_beauty(items: Vec<Vec<i32>>, queries: Vec<i32>) -> Vec<i32> {
+        let mut price_map = BTreeMap::new();
+
+        for item in items.iter() {
+            let entry = price_map.entry(item[0] as usize).or_insert(0);
+            *entry = (*entry).max(item[1]);
+        }
+
+        let mut query_map: BTreeMap<usize, i32> = BTreeMap::new();
+        let mut result = Vec::with_capacity(queries.len());
+
+        for price in queries {
+            let price = price as usize;
+            let (min_price, mut min_result) = match query_map.range(..=price).last() {
+                Some((&p, &r)) => (p, r),
+                None => (0, 0),
+            };
+
+            if min_price == price {
+                result.push(min_result);
+                continue;
+            }
+
+            for (&p, &r) in price_map.range(min_price + 1..=price) {
+                min_result = min_result.max(r);
+                query_map.insert(p, min_result);
+            }
+
+            result.push(min_result);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2070() {
+        assert_eq!(
+            vec![2, 4, 5, 5, 6, 6],
+            Solution::maximum_beauty(
+                vec![vec![1, 2], vec![3, 2], vec![2, 4], vec![5, 6], vec![3, 5]],
+                vec![1, 2, 3, 4, 5, 6]
+            )
+        );
+        assert_eq!(
+            vec![4],
+            Solution::maximum_beauty(
+                vec![vec![1, 2], vec![1, 2], vec![1, 3], vec![1, 4]],
+                vec![1]
+            )
+        );
+        assert_eq!(
+            vec![0],
+            Solution::maximum_beauty(vec![vec![10, 1000]], vec![5])
+        );
+    }
+}
diff --git a/src/problem/p2080_range_frequency_queries.rs b/src/problem/p2080_range_frequency_queries.rs
new file mode 100644
index 0000000..aa32b2a
--- /dev/null
+++ b/src/problem/p2080_range_frequency_queries.rs
@@ -0,0 +1,85 @@
+/**
+ * [2080] Range Frequency Queries
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+struct RangeFreqQuery {
+    frequency_map: HashMap<i32, Vec<usize>>,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl RangeFreqQuery {
+    fn new(arr: Vec<i32>) -> Self {
+        let mut frequency_map = HashMap::new();
+
+        for (i, v) in arr.into_iter().enumerate() {
+            let entry = frequency_map.entry(v).or_insert(vec![]);
+            entry.push(i);
+        }
+
+        Self { frequency_map }
+    }
+
+    fn query(&self, left: i32, right: i32, value: i32) -> i32 {
+        let (left, right) = (left as usize, right as usize);
+
+        if let Some(index) = self.frequency_map.get(&value) {
+            let l = index.binary_search(&left);
+            let r = index.binary_search(&right);
+
+            let result = match l {
+                Ok(l_ok) => match r {
+                    Ok(r_ok) => r_ok - l_ok + 1,
+                    Err(r_err) => r_err - l_ok,
+                },
+                Err(l_err) => match r {
+                    Ok(r_ok) => r_ok - l_err + 1,
+                    Err(r_err) => r_err - l_err,
+                },
+            };
+
+            result as i32
+        } else {
+            0
+        }
+    }
+}
+
+/**
+ * Your RangeFreqQuery object will be instantiated and called as such:
+ * let obj = RangeFreqQuery::new(arr);
+ * let ret_1: i32 = obj.query(left, right, value);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2080() {
+        let query = RangeFreqQuery::new(vec![12, 33, 4, 56, 22, 2, 34, 33, 22, 12, 34, 56]);
+
+        assert_eq!(1, query.query(1, 2, 4));
+        assert_eq!(2, query.query(0, 11, 33));
+
+        let query = RangeFreqQuery::new(vec![2, 2, 1, 2, 2]);
+
+        // [2]
+        assert_eq!(1, query.query(2, 4, 1));
+        assert_eq!(1, query.query(1, 3, 1));
+        assert_eq!(1, query.query(0, 2, 1));
+
+        let query = RangeFreqQuery::new(vec![1, 1, 1, 2, 2]);
+
+        // [0, 1, 2]
+        assert_eq!(1, query.query(2, 2, 1));
+    }
+}
diff --git a/src/problem/p2109_adding_spaces_to_a_string.rs b/src/problem/p2109_adding_spaces_to_a_string.rs
new file mode 100644
index 0000000..1a412e1
--- /dev/null
+++ b/src/problem/p2109_adding_spaces_to_a_string.rs
@@ -0,0 +1,50 @@
+/**
+ * [2109] Adding Spaces to a String
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn add_spaces(s: String, spaces: Vec<i32>) -> String {
+        let s: Vec<char> = s.chars().collect();
+        let mut result = Vec::with_capacity(s.len() + spaces.len());
+        let mut iter = spaces.into_iter().peekable();
+
+        for (i, v) in s.into_iter().enumerate() {
+            if let Some(&pos) = iter.peek() {
+                if i == pos as usize {
+                    iter.next();
+                    result.push(' ');
+                }
+            }
+
+            result.push(v);
+        }
+
+        result.into_iter().collect()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2109() {
+        assert_eq!(
+            "Leetcode Helps Me Learn",
+            Solution::add_spaces("LeetcodeHelpsMeLearn".to_owned(), vec![8, 13, 15])
+        );
+        assert_eq!(
+            "i code in py thon",
+            Solution::add_spaces("icodeinpython".to_owned(), vec![1, 5, 7, 9])
+        );
+        assert_eq!(
+            " s p a c i n g",
+            Solution::add_spaces("spacing".to_owned(), vec![0, 1, 2, 3, 4, 5, 6])
+        );
+    }
+}
diff --git a/src/problem/p2116_check_if_a_parentheses_string_can_be_valid.rs b/src/problem/p2116_check_if_a_parentheses_string_can_be_valid.rs
new file mode 100644
index 0000000..69529a7
--- /dev/null
+++ b/src/problem/p2116_check_if_a_parentheses_string_can_be_valid.rs
@@ -0,0 +1,80 @@
+/**
+ * [2116] Check if a Parentheses String Can Be Valid
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn can_be_valid(s: String, locked: String) -> bool {
+        let s: Vec<u8> = s.bytes().collect();
+        let locked: Vec<bool> = locked
+            .bytes()
+            .map(|x| if x == b'0' { false } else { true })
+            .collect();
+
+        if s.len() % 2 != 0 {
+            return false;
+        }
+
+        let mut locked_left = vec![];
+        let mut unlocked_pos = vec![];
+
+        for (i, &v) in s.iter().enumerate() {
+            if !locked[i] {
+                unlocked_pos.push(i);
+            } else {
+                if v == b'(' {
+                    locked_left.push(i);
+                } else {
+                    // 首先使用锁定的左括号匹配
+                    if locked_left.pop().is_none() {
+                        // 然后使用未锁定的位置修改
+                        if unlocked_pos.pop().is_none() {
+                            return false;
+                        }
+                    }
+                }
+            }
+        }
+
+        // 判断剩余的未锁定位置和锁定的左括号是否匹配
+        while let Some(left_pos) = locked_left.pop() {
+            if let Some(unlock_pos) = unlocked_pos.pop() {
+                if left_pos > unlock_pos {
+                    return false;
+                }
+            } else {
+                return false;
+            }
+        }
+
+        // 剩余的未锁定括号必须是偶数个
+        unlocked_pos.len() % 2 == 0
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2116() {
+        assert!(!Solution::can_be_valid(
+            "(((())".to_owned(),
+            "111111".to_owned()
+        ));
+        assert!(Solution::can_be_valid(
+            "))()))".to_owned(),
+            "010100".to_owned()
+        ));
+        assert!(Solution::can_be_valid("()()".to_owned(), "0000".to_owned()));
+        assert!(!Solution::can_be_valid(")".to_owned(), "0".to_owned()));
+        assert!(Solution::can_be_valid(
+            "(((())(((())".to_owned(),
+            "111111010111".to_owned()
+        ));
+    }
+}
diff --git a/src/problem/p2140_solving_questions_with_brainpower.rs b/src/problem/p2140_solving_questions_with_brainpower.rs
new file mode 100644
index 0000000..b5d5570
--- /dev/null
+++ b/src/problem/p2140_solving_questions_with_brainpower.rs
@@ -0,0 +1,56 @@
+/**
+ * [2140] Solving Questions With Brainpower
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn most_points(questions: Vec<Vec<i32>>) -> i64 {
+        let questions: Vec<(i64, usize)> = questions
+            .into_iter()
+            .map(|a| (a[0] as i64, a[1] as usize))
+            .collect();
+        let n = questions.len();
+        let mut dp = vec![0; n];
+
+        for i in (0..n).rev() {
+            let (score, brain_power) = questions[i];
+            dp[i] = if i == n - 1 { 0 } else { dp[i + 1] };
+
+            // 选择做i题就需要跳过brian_power道题
+            if i + brain_power + 1 < n {
+                dp[i] = dp[i].max(dp[i + brain_power + 1] + score);
+            } else {
+                dp[i] = dp[i].max(score);
+            }
+        }
+
+        dp[0]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2140() {
+        assert_eq!(
+            5,
+            Solution::most_points(vec![vec![3, 2], vec![4, 3], vec![4, 4], vec![2, 5]])
+        );
+        assert_eq!(
+            7,
+            Solution::most_points(vec![
+                vec![1, 1],
+                vec![2, 2],
+                vec![3, 3],
+                vec![4, 4],
+                vec![5, 5]
+            ])
+        );
+    }
+}
diff --git a/src/problem/p2145_count_the_hidden_sequences.rs b/src/problem/p2145_count_the_hidden_sequences.rs
new file mode 100644
index 0000000..90aa035
--- /dev/null
+++ b/src/problem/p2145_count_the_hidden_sequences.rs
@@ -0,0 +1,45 @@
+/**
+ * [2145] Count the Hidden Sequences
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn number_of_arrays(differences: Vec<i32>, lower: i32, upper: i32) -> i32 {
+        let mut min_value = 0i64;
+        let mut max_value = 0i64;
+        let mut last_value = 0i64;
+
+        for i in differences.into_iter() {
+            let value = last_value + i as i64;
+            min_value = min_value.min(value);
+            max_value = max_value.max(value);
+            last_value = value;
+        }
+
+        let range = max_value - min_value;
+
+        let result = (upper - lower + 1) as i64 - range;
+        if result > 0 {
+            result as i32
+        } else {
+            0
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2145() {
+        assert_eq!(60, Solution::number_of_arrays(vec![-40], -46, 53));
+        assert_eq!(2, Solution::number_of_arrays(vec![1, -3, 4], 1, 6));
+        assert_eq!(4, Solution::number_of_arrays(vec![3, -4, 5, 1, -2], -4, 5));
+        assert_eq!(0, Solution::number_of_arrays(vec![4, -7, 2], 3, 6));
+    }
+}
diff --git a/src/problem/p2176_count_equal_and_divisible_pairs_in_an_array.rs b/src/problem/p2176_count_equal_and_divisible_pairs_in_an_array.rs
new file mode 100644
index 0000000..151f4e4
--- /dev/null
+++ b/src/problem/p2176_count_equal_and_divisible_pairs_in_an_array.rs
@@ -0,0 +1,39 @@
+/**
+ * [2176] Count Equal and Divisible Pairs in an Array
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_pairs(nums: Vec<i32>, k: i32) -> i32 {
+        let k = k as usize;
+        let n = nums.len();
+
+        (0..n)
+            .into_iter()
+            .map(|x| (x + 1..n).into_iter().map(move |y| (x, y)))
+            .flatten()
+            .filter_map(|(i, j)| {
+                if nums[i] == nums[j] && i * j % k == 0 {
+                    Some(())
+                } else {
+                    None
+                }
+            })
+            .count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2176() {
+        assert_eq!(4, Solution::count_pairs(vec![3, 1, 2, 2, 2, 1, 3], 2));
+        assert_eq!(0, Solution::count_pairs(vec![1, 2, 3, 4], 1));
+    }
+}
diff --git a/src/problem/p2179_count_good_triplets_in_an_array.rs b/src/problem/p2179_count_good_triplets_in_an_array.rs
new file mode 100644
index 0000000..119e7fe
--- /dev/null
+++ b/src/problem/p2179_count_good_triplets_in_an_array.rs
@@ -0,0 +1,99 @@
+/**
+ * [2179] Count Good Triplets in an Array
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+struct FenwickTree {
+    tree: Vec<i64>,
+}
+
+impl FenwickTree {
+    fn new(size: usize) -> Self {
+        Self {
+            tree: vec![0; size + 1],
+        }
+    }
+
+    fn update(&mut self, mut index: usize, delta: i64) {
+        index += 1;
+
+        while index < self.tree.len() {
+            self.tree[index] += delta;
+
+            index += Self::low_bit(index)
+        }
+    }
+
+    fn query(&self, mut index: usize) -> i64 {
+        index += 1;
+        let mut result = 0;
+
+        while index > 0 {
+            result += self.tree[index];
+            index -= Self::low_bit(index)
+        }
+
+        result
+    }
+
+    // 二进制最低位1以及后面的0组成的数
+    fn low_bit(i: usize) -> usize {
+        i & (!i + 1)
+    }
+}
+
+impl Solution {
+    pub fn good_triplets(nums1: Vec<i32>, nums2: Vec<i32>) -> i64 {
+        let n = nums1.len();
+        // nums2中各个值到下标的映射数组
+        let mut pos2 = vec![0; n];
+        // index_mapping 是nums1中一个数在nums2中的下标
+        // reverse_index_mapping是该下标同nums1中数字下标的对应关系
+        let mut reversed_index_mapping = vec![0; n];
+
+        for (i, v) in nums2.iter().enumerate() {
+            pos2[*v as usize] = i;
+        }
+
+        for i in 0..n {
+            // nums1中的一个值在nums2中的下标到该值在nums1中的下标的映射
+            reversed_index_mapping[pos2[nums1[i] as usize]] = i;
+        }
+
+        let mut tree = FenwickTree::new(n);
+
+        let mut result = 0;
+
+        // 枚举num1s中的一个值在nums2中的下标
+        for j in 0..n {
+            let pos = reversed_index_mapping[j];
+            let left = tree.query(pos);
+            tree.update(pos, 1);
+            let right = ((n - 1 - pos) - (j - left as usize)) as i64;
+            result += left * right;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2179() {
+        assert_eq!(
+            1,
+            Solution::good_triplets(vec![2, 0, 1, 3], vec![0, 1, 2, 3])
+        );
+        assert_eq!(
+            4,
+            Solution::good_triplets(vec![4, 0, 1, 3, 2], vec![4, 1, 0, 2, 3])
+        );
+    }
+}
diff --git a/src/problem/p2209_minimum_white_tiles_after_covering_with_carpets.rs b/src/problem/p2209_minimum_white_tiles_after_covering_with_carpets.rs
new file mode 100644
index 0000000..cb4852b
--- /dev/null
+++ b/src/problem/p2209_minimum_white_tiles_after_covering_with_carpets.rs
@@ -0,0 +1,68 @@
+use std::ffi::FromVecWithNulError;
+
+/**
+ * [2209] Minimum White Tiles After Covering With Carpets
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn minimum_white_tiles(floor: String, num_carpets: i32, carpet_len: i32) -> i32 {
+        let carpets_num = num_carpets as usize;
+        let carpet_length = carpet_len as usize;
+        let floor: Vec<bool> = floor
+            .chars()
+            .into_iter()
+            .map(|x| if x == '0' { true } else { false })
+            .collect();
+
+        // dp[i][j] 表示
+        // 当使用j块地毯时
+        // [i..] 还有多少白色的地砖没有被覆盖
+        let mut dp = vec![vec![0; carpets_num + 1]; floor.len()];
+
+        // 初始化dp[i][0]
+        let mut white_count = 0;
+        for i in (0..floor.len()).rev() {
+            if !floor[i] {
+                white_count += 1;
+            }
+            dp[i][0] = white_count;
+        }
+
+        for i in (0..floor.len() - 1).rev() {
+            for j in 1..=carpets_num {
+                // 在floor[i]处不放置地毯
+                let a = dp[i + 1][j] + if !floor[i] { 1 } else { 0 };
+                // 在floor[i]处放置地毯
+                // 如果放置的长度超过地板的总长
+                // 则剩余的白色地砖数量必然为0
+                let b = if i + carpet_length >= floor.len() {
+                    0
+                } else {
+                    dp[i + carpet_length][j - 1]
+                };
+                dp[i][j] = a.min(b);
+            }
+        }
+
+        dp[0][carpets_num]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2209() {
+        assert_eq!(0, Solution::minimum_white_tiles("11111".to_owned(), 2, 3));
+        assert_eq!(
+            2,
+            Solution::minimum_white_tiles("10110101".to_owned(), 2, 2)
+        );
+    }
+}
diff --git a/src/problem/p2234_maximum_total_beauty_of_the_gardens.rs b/src/problem/p2234_maximum_total_beauty_of_the_gardens.rs
new file mode 100644
index 0000000..e41f6ac
--- /dev/null
+++ b/src/problem/p2234_maximum_total_beauty_of_the_gardens.rs
@@ -0,0 +1,78 @@
+/**
+ * [2234] Maximum Total Beauty of the Gardens
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn maximum_beauty(
+        mut flowers: Vec<i32>,
+        new_flowers: i64,
+        target: i32,
+        full: i32,
+        partial: i32,
+    ) -> i64 {
+        let n = flowers.len();
+        let target = target as i64;
+        let full = full as i64;
+        let partial = partial as i64;
+
+        let mut flowers: Vec<i64> = flowers
+            .into_iter()
+            .map(|x| (x as i64).min(target))
+            .collect();
+
+        flowers.sort_unstable_by(|a, b| b.cmp(a));
+
+        let mut result = 0;
+        let mut sum: i64 = flowers.iter().map(|x| *x).sum();
+        if target * n as i64 - sum <= new_flowers {
+            result += full * n as i64;
+        }
+
+        let mut prefix = 0;
+        let mut ptr = 0;
+
+        for i in 0..n {
+            if i != 0 {
+                prefix += flowers[i - 1];
+            }
+
+            if flowers[i] == target {
+                continue;
+            }
+
+            let mut rest = new_flowers - (target * i as i64 - prefix);
+            if rest < 0 {
+                break;
+            }
+
+            while !(ptr >= i && flowers[ptr] * (n - ptr) as i64 - sum <= rest) {
+                sum -= flowers[ptr];
+                ptr += 1;
+            }
+
+            rest -= flowers[ptr] * (n - ptr) as i64 - sum;
+            result = result.max(
+                full * i as i64
+                    + partial * (flowers[ptr] + rest / (n - ptr) as i64).min(target - 1),
+            );
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2234() {
+        assert_eq!(14, Solution::maximum_beauty(vec![1, 3, 1, 1], 7, 6, 12, 1));
+        assert_eq!(30, Solution::maximum_beauty(vec![2, 4, 5, 3], 10, 5, 2, 6));
+    }
+}
diff --git a/src/problem/p2255_count_prefixes_of_a_given_string.rs b/src/problem/p2255_count_prefixes_of_a_given_string.rs
new file mode 100644
index 0000000..c8b0a02
--- /dev/null
+++ b/src/problem/p2255_count_prefixes_of_a_given_string.rs
@@ -0,0 +1,34 @@
+/**
+ * [2255] Count Prefixes of a Given String
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_prefixes(words: Vec<String>, s: String) -> i32 {
+        words.iter().filter(|i| s.starts_with(i.as_str())).count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2255() {
+        assert_eq!(
+            3,
+            Solution::count_prefixes(
+                vec_string!("a", "b", "c", "ab", "bc", "abc"),
+                "abc".to_owned()
+            )
+        );
+        assert_eq!(
+            2,
+            Solution::count_prefixes(vec_string!("a", "a"), "aa".to_owned())
+        );
+    }
+}
diff --git a/src/problem/p2269_find_the_k_beauty_of_a_number.rs b/src/problem/p2269_find_the_k_beauty_of_a_number.rs
new file mode 100644
index 0000000..68a5e66
--- /dev/null
+++ b/src/problem/p2269_find_the_k_beauty_of_a_number.rs
@@ -0,0 +1,36 @@
+/**
+ * [2269] Find the K-Beauty of a Number
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn divisor_substrings(num: i32, k: i32) -> i32 {
+        let k = k as usize;
+        let num_str: Vec<char> = num.to_string().chars().collect();
+
+        (0..=num_str.len() - k)
+            .into_iter()
+            .map(|i| {
+                (&num_str[i..i + k])
+                    .iter()
+                    .fold(0i32, |v, c| v * 10 + c.to_digit(10).unwrap() as i32)
+            })
+            .filter(|&v| v != 0 && num % v == 0)
+            .count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2269() {
+        assert_eq!(2, Solution::divisor_substrings(240, 2));
+        assert_eq!(2, Solution::divisor_substrings(430043, 2));
+    }
+}
diff --git a/src/problem/p2272_substring_with_largest_variance.rs b/src/problem/p2272_substring_with_largest_variance.rs
new file mode 100644
index 0000000..7ac1570
--- /dev/null
+++ b/src/problem/p2272_substring_with_largest_variance.rs
@@ -0,0 +1,58 @@
+/**
+ * [2272] Substring With Largest Variance
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn largest_variance(s: String) -> i32 {
+        let word: Vec<char> = s.chars().collect();
+        let mut pos_map = HashMap::new();
+
+        for (i, c) in word.into_iter().enumerate() {
+            let entry = pos_map.entry(c).or_insert(vec![]);
+            entry.push(i);
+        }
+
+        let mut result = 0;
+
+        for (c0, pos0) in pos_map.iter() {
+            for (c1, pos1) in pos_map.iter() {
+                if c0 != c1 {
+                    let (mut i, mut j) = (0, 0);
+                    let (mut f, mut g) = (0, i32::MIN);
+
+                    // 这里的算法类似于合并两个有序列表
+                    while i < pos0.len() || j < pos1.len() {
+                        if j == pos1.len() || (i < pos0.len() && pos0[i] < pos1[j]) {
+                            (f, g) = (f.max(0) + 1, g + 1);
+                            i += 1;
+                        } else {
+                            (f, g) = (f.max(0) - 1, f.max(g).max(0) - 1);
+                            j += 1;
+                        }
+
+                        result = result.max(g);
+                    }
+                }
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2272() {
+        assert_eq!(3, Solution::largest_variance("aababbb".to_owned()));
+        assert_eq!(0, Solution::largest_variance("abcde".to_owned()));
+    }
+}
diff --git a/src/problem/p2278_percentage_of_letter_in_string.rs b/src/problem/p2278_percentage_of_letter_in_string.rs
new file mode 100644
index 0000000..5b27b71
--- /dev/null
+++ b/src/problem/p2278_percentage_of_letter_in_string.rs
@@ -0,0 +1,25 @@
+/**
+ * [2278] Percentage of Letter in String
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn percentage_letter(s: String, letter: char) -> i32 {
+        (s.chars().filter(|c| *c == letter).count() * 100 / s.len()) as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2278() {
+        assert_eq!(33, Solution::percentage_letter("foobar".to_owned(), 'o'));
+        assert_eq!(0, Solution::percentage_letter("jjjj".to_owned(), 'k'));
+    }
+}
diff --git a/src/problem/p2338_count_the_number_of_ideal_arrays.rs b/src/problem/p2338_count_the_number_of_ideal_arrays.rs
new file mode 100644
index 0000000..0960c00
--- /dev/null
+++ b/src/problem/p2338_count_the_number_of_ideal_arrays.rs
@@ -0,0 +1,81 @@
+/**
+ * [2338] Count the Number of Ideal Arrays
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+const MOD: usize = 1_000_000_007;
+const MAX_N: usize = 10010;
+const MAX_P: usize = 15;
+
+impl Solution {
+    pub fn ideal_arrays(n: i32, max_value: i32) -> i32 {
+        let mut result = 0usize;
+        let n = n as usize;
+        let (prime_sieves, dp) = Self::calculate_dp_array();
+
+        for x in 1..=max_value {
+            let mut current = 1;
+            for &p in prime_sieves[x as usize].iter() {
+                current = current * dp[n + p - 1][p] % MOD;
+            }
+            result = (result + current) % MOD;
+        }
+
+        result as i32
+    }
+
+    fn calculate_dp_array() -> (Vec<Vec<usize>>, Vec<Vec<usize>>) {
+        // 最小质因数列表
+        let mut sieves = vec![0; MAX_N];
+
+        for i in 2..MAX_N {
+            if sieves[i] == 0 {
+                for j in (i..MAX_N).step_by(i) {
+                    sieves[j] = i;
+                }
+            }
+        }
+
+        let mut prime_sieves = vec![vec![]; MAX_N];
+        for i in 2..MAX_N {
+            let mut x = i;
+
+            while x > 1 {
+                let p = sieves[x];
+                let mut current = 0;
+                while x % p == 0 {
+                    x /= p;
+                    current += 1;
+                }
+
+                prime_sieves[i].push(current);
+            }
+        }
+
+        let mut dp = vec![vec![0usize; MAX_P + 1]; MAX_N + MAX_P];
+        dp[0][0] = 1;
+        for i in 1..(MAX_N + MAX_P) {
+            dp[i][0] = 1;
+            for j in 1..(i.min(MAX_P) + 1) {
+                dp[i][j] = (dp[i - 1][j] + dp[i - 1][j - 1]) % MOD;
+            }
+        }
+
+        (prime_sieves, dp)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2338() {
+        assert_eq!(10, Solution::ideal_arrays(2, 5));
+        assert_eq!(11, Solution::ideal_arrays(5, 3));
+    }
+}
diff --git a/src/problem/p2353_design_a_food_rating_system.rs b/src/problem/p2353_design_a_food_rating_system.rs
new file mode 100644
index 0000000..4587f89
--- /dev/null
+++ b/src/problem/p2353_design_a_food_rating_system.rs
@@ -0,0 +1,137 @@
+/**
+ * [2353] Design a Food Rating System
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::cmp::Ordering;
+use std::collections::{BinaryHeap, HashMap};
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+struct Food {
+    name: String,
+    cuisine: String,
+    rating: i32,
+}
+
+impl Food {
+    fn new(name: String, cuisine: String, rating: i32) -> Self {
+        Self {
+            name,
+            cuisine,
+            rating,
+        }
+    }
+
+    fn update_rating(&self, new_rating: i32) -> Self {
+        Self {
+            name: self.name.clone(),
+            cuisine: self.cuisine.clone(),
+            rating: new_rating,
+        }
+    }
+}
+
+impl Ord for Food {
+    fn cmp(&self, other: &Self) -> Ordering {
+        match self.rating.cmp(&other.rating) {
+            Ordering::Equal => other.name.cmp(&self.name),
+            a => a,
+        }
+    }
+}
+
+impl PartialOrd for Food {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+struct FoodRatings {
+    food_map: HashMap<String, Food>,
+    cuisine_heap: HashMap<String, BinaryHeap<Food>>,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl FoodRatings {
+    fn new(foods: Vec<String>, cuisines: Vec<String>, ratings: Vec<i32>) -> Self {
+        let mut food_map = HashMap::new();
+        let mut cuisine_heap = HashMap::new();
+
+        for ((name, cuisine), &rating) in foods.iter().zip(cuisines.iter()).zip(ratings.iter()) {
+            food_map.insert(
+                name.clone(),
+                Food::new(name.clone(), cuisine.clone(), rating),
+            );
+
+            let heap = cuisine_heap
+                .entry(cuisine.clone())
+                .or_insert(BinaryHeap::new());
+            heap.push(Food::new(name.clone(), cuisine.clone(), rating.clone()));
+        }
+
+        Self {
+            food_map,
+            cuisine_heap,
+        }
+    }
+
+    fn change_rating(&mut self, food: String, new_rating: i32) {
+        let food_entry = self.food_map.get_mut(&food).unwrap();
+        food_entry.rating = new_rating;
+
+        let heap = self.cuisine_heap.get_mut(&food_entry.cuisine).unwrap();
+        heap.push(food_entry.update_rating(new_rating));
+    }
+
+    fn highest_rated(&mut self, cuisine: String) -> String {
+        let heap = self.cuisine_heap.get_mut(&cuisine).unwrap();
+
+        while let Some(head) = heap.peek() {
+            let food_entry = self.food_map.get(&head.name).unwrap();
+
+            if head.rating == food_entry.rating {
+                return food_entry.name.clone();
+            }
+
+            heap.pop();
+        }
+
+        "".to_owned()
+    }
+}
+
+/**
+ * Your FoodRatings object will be instantiated and called as such:
+ * let obj = FoodRatings::new(foods, cuisines, ratings);
+ * obj.change_rating(food, newRating);
+ * let ret_2: String = obj.highest_rated(cuisine);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2353() {
+        let mut ratings = FoodRatings::new(
+            vec_string!("kimchi", "miso", "sushi", "moussaka", "ramen", "bulgogi"),
+            vec_string!("korean", "japanese", "japanese", "greek", "japanese", "korean"),
+            vec![9, 12, 8, 15, 14, 7],
+        );
+
+        assert_eq!("kimchi", ratings.highest_rated("korean".to_owned()));
+        assert_eq!("ramen", ratings.highest_rated("japanese".to_owned()));
+
+        ratings.change_rating("sushi".to_owned(), 16);
+        assert_eq!("sushi", ratings.highest_rated("japanese".to_owned()));
+
+        ratings.change_rating("ramen".to_owned(), 16);
+        assert_eq!("ramen", ratings.highest_rated("japanese".to_owned()));
+    }
+}
diff --git a/src/problem/p2360_longest_cycle_in_a_graph.rs b/src/problem/p2360_longest_cycle_in_a_graph.rs
new file mode 100644
index 0000000..1b175af
--- /dev/null
+++ b/src/problem/p2360_longest_cycle_in_a_graph.rs
@@ -0,0 +1,55 @@
+/**
+ * [2360] Longest Cycle in a Graph
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn longest_cycle(edges: Vec<i32>) -> i32 {
+        let n = edges.len();
+        let mut labels = vec![0; n];
+
+        let mut current_label = 0;
+        let mut result = -1;
+
+        for i in 0..n {
+            if labels[i] != 0 {
+                continue;
+            }
+
+            let mut pos = i as i32;
+            let start_label = current_label;
+
+            while pos != -1 {
+                current_label += 1;
+                // 遇到已经遍历过的节点
+                let real_pos = pos as usize;
+                if labels[real_pos] != 0 {
+                    if labels[real_pos] > start_label {
+                        result = result.max(current_label - labels[real_pos]);
+                    }
+                    break;
+                }
+
+                labels[real_pos] = current_label;
+                pos = edges[real_pos];
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2360() {
+        assert_eq!(3, Solution::longest_cycle(vec![3, 3, 4, 2, 3]));
+        assert_eq!(-1, Solution::longest_cycle(vec![2, -1, 3, 1]));
+    }
+}
diff --git a/src/problem/p2364_count_number_of_bad_pairs.rs b/src/problem/p2364_count_number_of_bad_pairs.rs
new file mode 100644
index 0000000..f390541
--- /dev/null
+++ b/src/problem/p2364_count_number_of_bad_pairs.rs
@@ -0,0 +1,41 @@
+/**
+ * [2364] Count Number of Bad Pairs
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn count_bad_pairs(nums: Vec<i32>) -> i64 {
+        let n = nums.len() as i64;
+        let mut map = HashMap::new();
+
+        for (i, v) in nums.into_iter().enumerate() {
+            let delta = v - i as i32;
+            let mut entry = map.entry(delta).or_insert(0);
+            *entry += 1;
+        }
+
+        // 反过来计算好数对的数量
+        let good_pair_count = map
+            .values()
+            .filter_map(|&v| if v >= 2 { Some(v * (v - 1) / 2) } else { None })
+            .sum::<i64>();
+
+        n * (n - 1) / 2 - good_pair_count
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2364() {
+        assert_eq!(5, Solution::count_bad_pairs(vec![4, 1, 3, 3]));
+        assert_eq!(0, Solution::count_bad_pairs(vec![1, 2, 3, 4, 5]));
+    }
+}
diff --git a/src/problem/p2502_design_memory_allocator.rs b/src/problem/p2502_design_memory_allocator.rs
new file mode 100644
index 0000000..9f73961
--- /dev/null
+++ b/src/problem/p2502_design_memory_allocator.rs
@@ -0,0 +1,105 @@
+/**
+ * [2502] Design Memory Allocator
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+struct Allocator {
+    memory: Vec<bool>,
+    id_map: HashMap<i32, Vec<(usize, usize)>>,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl Allocator {
+    fn new(n: i32) -> Self {
+        let n = n as usize;
+        Self {
+            memory: vec![false; n],
+            id_map: HashMap::new(),
+        }
+    }
+
+    fn allocate(&mut self, size: i32, m_id: i32) -> i32 {
+        let size = size as usize;
+        let mut start = 0;
+
+        while start < self.memory.len() {
+            let mut pos = start;
+            while pos < self.memory.len() && !self.memory[pos] {
+                if pos - start + 1 == size {
+                    for i in start..=pos {
+                        self.memory[i] = true;
+                    }
+
+                    let entry = self.id_map.entry(m_id).or_insert(vec![]);
+                    entry.push((start, pos));
+                    return start as i32;
+                }
+
+                pos += 1;
+            }
+
+            // 到达这里只能说明找到的空间不足
+            start = pos + 1;
+        }
+
+        -1
+    }
+
+    fn free_memory(&mut self, m_id: i32) -> i32 {
+        if let Some(array) = self.id_map.get(&m_id) {
+            let mut length = 0;
+
+            for &(start, end) in array.iter() {
+                for i in start..=end {
+                    self.memory[i] = false;
+                }
+                length += (end - start + 1) as i32;
+            }
+
+            self.id_map.remove(&m_id);
+            length
+        } else {
+            0
+        }
+    }
+}
+
+/**
+ * Your Allocator object will be instantiated and called as such:
+ * let obj = Allocator::new(n);
+ * let ret_1: i32 = obj.allocate(size, mID);
+ * let ret_2: i32 = obj.free_memory(mID);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2502() {
+        let mut allocator = Allocator::new(10);
+
+        assert_eq!(0, allocator.allocate(1, 1));
+        assert_eq!(1, allocator.allocate(1, 2));
+        assert_eq!(2, allocator.allocate(1, 3));
+
+        assert_eq!(1, allocator.free_memory(2));
+
+        assert_eq!(3, allocator.allocate(3, 4));
+        assert_eq!(1, allocator.allocate(1, 1));
+        assert_eq!(6, allocator.allocate(1, 1));
+
+        assert_eq!(3, allocator.free_memory(1));
+
+        assert_eq!(-1, allocator.allocate(10, 2));
+        assert_eq!(0, allocator.free_memory(7));
+    }
+}
diff --git a/src/problem/p2506_count_pairs_of_similar_strings.rs b/src/problem/p2506_count_pairs_of_similar_strings.rs
new file mode 100644
index 0000000..029cb20
--- /dev/null
+++ b/src/problem/p2506_count_pairs_of_similar_strings.rs
@@ -0,0 +1,50 @@
+/**
+ * [2506] Count Pairs Of Similar Strings
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn similar_pairs(words: Vec<String>) -> i32 {
+        let mut map = HashMap::new();
+
+        for word in words.iter() {
+            let mut bits = 0;
+
+            for c in word.chars() {
+                bits = bits | (1 << (c as u8 - 'a' as u8))
+            }
+
+            let entry = map.entry(bits).or_insert(0);
+            *entry += 1;
+        }
+
+        let mut result = 0;
+
+        for &v in map.values() {
+            // C(n, 2)
+            result += v * (v - 1) / 2;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2506() {
+        assert_eq!(
+            2,
+            Solution::similar_pairs(vec_string!("aba", "aabb", "abcd", "bac", "aabc"))
+        );
+        assert_eq!(3, Solution::similar_pairs(vec_string!("aabb", "ab", "ba")));
+        assert_eq!(0, Solution::similar_pairs(vec_string!("nba", "cba", "dba")));
+    }
+}
diff --git a/src/problem/p2537_count_the_number_of_good_subarrays.rs b/src/problem/p2537_count_the_number_of_good_subarrays.rs
new file mode 100644
index 0000000..de19f69
--- /dev/null
+++ b/src/problem/p2537_count_the_number_of_good_subarrays.rs
@@ -0,0 +1,58 @@
+/**
+ * [2537] Count the Number of Good Subarrays
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn count_good(nums: Vec<i32>, k: i32) -> i64 {
+        let mut map = HashMap::new();
+        let n = nums.len();
+
+        let mut result = 0i64;
+        let mut count = 0;
+        let (mut left, mut right) = (0, 0);
+
+        while left < n {
+            while right < n && count < k {
+                let entry = map.entry(nums[right]).or_insert(0);
+                count += *entry;
+                *entry += 1;
+
+                right += 1;
+            }
+
+            if count < k && right >= n {
+                // 拼尽全力无法战胜
+                break;
+            }
+
+            // 此时已经遇到了一个合格的序列
+            // 注意序列可以多余的包含右侧的所有元素
+            result += (n - right) as i64 + 1;
+
+            // 右移left
+            let entry = map.entry(nums[left]).or_insert(0);
+            count -= *entry - 1;
+            *entry -= 1;
+            left += 1;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2537() {
+        assert_eq!(4, Solution::count_good(vec![3, 1, 4, 3, 2, 2, 4], 2));
+        assert_eq!(1, Solution::count_good(vec![1, 1, 1, 1, 1], 10));
+    }
+}
diff --git a/src/problem/p2563_count_the_number_of_fair_pairs.rs b/src/problem/p2563_count_the_number_of_fair_pairs.rs
new file mode 100644
index 0000000..22cc2c1
--- /dev/null
+++ b/src/problem/p2563_count_the_number_of_fair_pairs.rs
@@ -0,0 +1,35 @@
+/**
+ * [2563] Count the Number of Fair Pairs
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_fair_pairs(mut nums: Vec<i32>, lower: i32, upper: i32) -> i64 {
+        nums.sort_unstable();
+        let mut result = 0;
+
+        for i in 0..nums.len() {
+            let l = nums[0..i].partition_point(|&x| x + nums[i] < lower);
+            let r = nums[0..i].partition_point(|&x| x + nums[i] <= upper);
+
+            result += r - l;
+        }
+
+        result as i64
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2563() {
+        assert_eq!(6, Solution::count_fair_pairs(vec![0, 1, 7, 4, 4, 5], 3, 6));
+        assert_eq!(1, Solution::count_fair_pairs(vec![1, 7, 9, 2, 5], 11, 11));
+    }
+}
diff --git a/src/problem/p2588_count_the_number_of_beautiful_subarrays.rs b/src/problem/p2588_count_the_number_of_beautiful_subarrays.rs
new file mode 100644
index 0000000..dfe2573
--- /dev/null
+++ b/src/problem/p2588_count_the_number_of_beautiful_subarrays.rs
@@ -0,0 +1,45 @@
+/**
+ * [2588] Count the Number of Beautiful Subarrays
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn beautiful_subarrays(nums: Vec<i32>) -> i64 {
+        let n = nums.len();
+        let mut prefix = vec![0; n + 1];
+
+        for i in 0..n {
+            prefix[i + 1] = prefix[i] ^ nums[i];
+        }
+
+        let mut map = HashMap::new();
+
+        let mut result = 0;
+        for i in 0..=n {
+            if let Some(count) = map.get(&prefix[i]) {
+                result += count;
+            }
+
+            let entry = map.entry(prefix[i] ^ 0).or_insert(0);
+            *entry += 1;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2588() {
+        assert_eq!(2, Solution::beautiful_subarrays(vec![4, 3, 1, 2, 4]));
+        assert_eq!(0, Solution::beautiful_subarrays(vec![1, 10, 4]));
+    }
+}
diff --git a/src/problem/p2595_number_of_even_and_odd_bits.rs b/src/problem/p2595_number_of_even_and_odd_bits.rs
new file mode 100644
index 0000000..4bb710b
--- /dev/null
+++ b/src/problem/p2595_number_of_even_and_odd_bits.rs
@@ -0,0 +1,43 @@
+/**
+ * [2595] Number of Even and Odd Bits
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn even_odd_bit(mut n: i32) -> Vec<i32> {
+        let mut is_even = true;
+        let mut even_count = 0;
+        let mut odd_count = 0;
+
+        while n > 0 {
+            let bit = n % 2;
+            if bit == 1 {
+                if is_even {
+                    even_count += 1;
+                } else {
+                    odd_count += 1;
+                }
+            }
+
+            is_even = !is_even;
+            n = n / 2;
+        }
+
+        vec![even_count, odd_count]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2595() {
+        assert_eq!(vec![1, 2], Solution::even_odd_bit(50));
+        assert_eq!(vec![0, 1], Solution::even_odd_bit(2));
+    }
+}
diff --git a/src/problem/p2597_the_number_of_beautiful_subsets.rs b/src/problem/p2597_the_number_of_beautiful_subsets.rs
new file mode 100644
index 0000000..599ff33
--- /dev/null
+++ b/src/problem/p2597_the_number_of_beautiful_subsets.rs
@@ -0,0 +1,64 @@
+/**
+ * [2597] The Number of Beautiful Subsets
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::{BTreeMap, HashMap};
+
+impl Solution {
+    pub fn beautiful_subsets(nums: Vec<i32>, k: i32) -> i32 {
+        let mut map = HashMap::new();
+
+        for i in nums {
+            let value = i % k;
+            let entry = map.entry(value).or_insert(BTreeMap::new());
+            let group_entry = entry.entry(i).or_insert(0);
+            *group_entry += 1;
+        }
+
+        let mut result = 1;
+
+        for group in map.values() {
+            let n = group.len();
+            // (x, y) x表示不选择第i个数
+            // y表示选择第i个数
+            let mut dp = vec![(0, 0); n];
+            // 懒得用迭代器移来移去
+            // 直接复制到数组开干
+            let array: Vec<(i32, i32)> = group.iter().map(|(x, y)| (*x, *y)).collect();
+
+            for (i, &(key, count)) in array.iter().enumerate() {
+                if i == 0 {
+                    dp[0].0 = 1;
+                    dp[0].1 = (1 << count) - 1;
+                } else {
+                    dp[i].0 = dp[i - 1].0 + dp[i - 1].1;
+
+                    if key - array[i - 1].0 == k {
+                        dp[i].1 = dp[i - 1].0 * ((1 << count) - 1);
+                    } else {
+                        dp[i].1 = (dp[i - 1].0 + dp[i - 1].1) * ((1 << count) - 1);
+                    }
+                }
+            }
+
+            result *= dp[n - 1].0 + dp[n - 1].1;
+        }
+
+        result - 1
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2597() {
+        assert_eq!(4, Solution::beautiful_subsets(vec![2, 4, 6], 2));
+        assert_eq!(1, Solution::beautiful_subsets(vec![1], 1));
+    }
+}
diff --git a/src/problem/p2610_convert_an_array_into_a_2d_array_with_conditions.rs b/src/problem/p2610_convert_an_array_into_a_2d_array_with_conditions.rs
new file mode 100644
index 0000000..b97f46c
--- /dev/null
+++ b/src/problem/p2610_convert_an_array_into_a_2d_array_with_conditions.rs
@@ -0,0 +1,47 @@
+/**
+ * [2610] Convert an Array Into a 2D Array With Conditions
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn find_matrix(nums: Vec<i32>) -> Vec<Vec<i32>> {
+        let mut result = vec![];
+        let mut map = HashMap::new();
+
+        for i in nums {
+            let entry = map.entry(i).or_insert(0);
+            *entry += 1;
+        }
+
+        while !map.is_empty() {
+            let mut row = Vec::with_capacity(map.len());
+            for (k, v) in map.iter_mut() {
+                row.push(*k);
+                *v -= 1;
+            }
+
+            map.retain(|_, &mut x| x != 0);
+            result.push(row);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2610() {
+        assert_inner_array_unorder_equal!(
+            vec![vec![1, 3, 4, 2], vec![1, 3], vec![1]],
+            Solution::find_matrix(vec![1, 3, 4, 1, 2, 3, 1]),
+        );
+    }
+}
diff --git a/src/problem/p2612_minimum_reverse_operations.rs b/src/problem/p2612_minimum_reverse_operations.rs
new file mode 100644
index 0000000..dcaf5b3
--- /dev/null
+++ b/src/problem/p2612_minimum_reverse_operations.rs
@@ -0,0 +1,89 @@
+/**
+ * [2612] Minimum Reverse Operations
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::{BTreeSet, HashSet, VecDeque};
+use std::iter::FromIterator;
+
+impl Solution {
+    pub fn min_reverse_operations(n: i32, p: i32, banned: Vec<i32>, k: i32) -> Vec<i32> {
+        let (n, p) = (n as usize, p as usize);
+        let mut ban_pos: HashSet<usize> =
+            HashSet::from_iter(banned.into_iter().map(|x| x as usize));
+        // 奇数下标和偶数下标是分别连续的
+        // 使用两个二叉树维护
+        let mut odd_pos = BTreeSet::new();
+        let mut even_pos = BTreeSet::new();
+
+        for i in 0..n {
+            if i != p && !ban_pos.contains(&i) {
+                if i % 2 == 0 {
+                    even_pos.insert(i);
+                } else {
+                    odd_pos.insert(i);
+                }
+            }
+        }
+
+        let mut result = vec![-1; n];
+        let mut queue = VecDeque::new();
+        queue.push_back(p);
+        result[p] = 0;
+
+        while let Some(front) = queue.pop_front() {
+            // 为了防止usize溢出的诡异类型转换
+            let min_pos = (front as i32 - k + 1).max(k - front as i32 - 1) as usize;
+            let max_pos = (front as i32 + k - 1).min(n as i32 * 2 - k - front as i32 - 1) as usize;
+
+            let mut iter = if max_pos % 2 == 0 {
+                even_pos.range(min_pos..)
+            } else {
+                odd_pos.range(min_pos..)
+            };
+
+            while let Some(&value) = iter.next() {
+                if value > max_pos {
+                    break;
+                }
+
+                result[value] = result[front] + 1;
+                queue.push_back(value);
+
+                iter = if min_pos % 2 == 0 {
+                    even_pos.remove(&value);
+                    even_pos.range(value + 1..)
+                } else {
+                    odd_pos.remove(&value);
+                    odd_pos.range(value + 1..)
+                }
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2612() {
+        assert_eq!(
+            vec![0, -1, -1, 1],
+            Solution::min_reverse_operations(4, 0, vec![1, 2], 4)
+        );
+        assert_eq!(
+            vec![0, -1, -1, -1, -1],
+            Solution::min_reverse_operations(5, 0, vec![2, 4], 3)
+        );
+        assert_eq!(
+            vec![-1, -1, 0, -1],
+            Solution::min_reverse_operations(4, 2, vec![0, 1, 3], 1)
+        );
+    }
+}
diff --git a/src/problem/p2614_prime_in_diagonal.rs b/src/problem/p2614_prime_in_diagonal.rs
new file mode 100644
index 0000000..80efa88
--- /dev/null
+++ b/src/problem/p2614_prime_in_diagonal.rs
@@ -0,0 +1,52 @@
+/**
+ * [2614] Prime In Diagonal
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn diagonal_prime(nums: Vec<Vec<i32>>) -> i32 {
+        let n = nums.len();
+        let mut result = 0;
+
+        for i in 0..n {
+            if Self::is_prime(nums[i][i]) {
+                result = result.max(nums[i][i]);
+            }
+
+            if Self::is_prime(nums[i][n - i - 1]) {
+                result = result.max(nums[i][n - i - 1]);
+            }
+        }
+
+        result
+    }
+
+    fn is_prime(num: i32) -> bool {
+        if num == 1 {
+            return false;
+        }
+
+        !(2..=num.isqrt()).any(|x| num % x == 0)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2614() {
+        assert_eq!(
+            11,
+            Solution::diagonal_prime(vec![vec![1, 2, 3], vec![5, 6, 7], vec![9, 10, 11]])
+        );
+        assert_eq!(
+            17,
+            Solution::diagonal_prime(vec![vec![1, 2, 3], vec![5, 17, 7], vec![9, 10, 11]])
+        );
+    }
+}
diff --git a/src/problem/p2643_row_with_maximum_ones.rs b/src/problem/p2643_row_with_maximum_ones.rs
new file mode 100644
index 0000000..b16058f
--- /dev/null
+++ b/src/problem/p2643_row_with_maximum_ones.rs
@@ -0,0 +1,48 @@
+/**
+ * [2643] Row With Maximum Ones
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn row_and_maximum_ones(mat: Vec<Vec<i32>>) -> Vec<i32> {
+        let r = mat.iter().enumerate().rev().fold(
+            (mat.len() - 1, 0),
+            |(r_line, r_count), (line, row)| {
+                let c = row.iter().filter(|x| **x == 1).count();
+
+                if c >= r_count {
+                    (line, c)
+                } else {
+                    (r_line, r_count)
+                }
+            },
+        );
+
+        vec![r.0 as i32, r.1 as i32]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2643() {
+        assert_eq!(
+            vec![0, 1],
+            Solution::row_and_maximum_ones(vec![vec![0, 1], vec![1, 0]])
+        );
+        assert_eq!(
+            vec![1, 2],
+            Solution::row_and_maximum_ones(vec![vec![0, 0, 0], vec![0, 1, 1]])
+        );
+        assert_eq!(
+            vec![1, 2],
+            Solution::row_and_maximum_ones(vec![vec![0, 0], vec![1, 1], vec![0, 0]])
+        );
+    }
+}
diff --git a/src/problem/p2680_maximum_or.rs b/src/problem/p2680_maximum_or.rs
new file mode 100644
index 0000000..f9b940a
--- /dev/null
+++ b/src/problem/p2680_maximum_or.rs
@@ -0,0 +1,46 @@
+/**
+ * [2680] Maximum OR
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn maximum_or(nums: Vec<i32>, k: i32) -> i64 {
+        let n = nums.len();
+        let k = k as i64;
+        let mut prefix = vec![0; n];
+        let mut suffix = vec![0; n];
+
+        for i in 0..n {
+            if i == 0 {
+                prefix[i] = 0;
+                suffix[n - i - 1] = 0;
+            } else {
+                prefix[i] = prefix[i - 1] | nums[i - 1] as i64;
+                suffix[n - i - 1] = suffix[n - i] | nums[n - i] as i64;
+            }
+        }
+
+        let mut result = 0;
+
+        for (i, &v) in nums.iter().enumerate() {
+            result = result.max(prefix[i] | ((v as i64) << k) | suffix[i]);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2680() {
+        assert_eq!(30, Solution::maximum_or(vec![12, 9], 1));
+        assert_eq!(35, Solution::maximum_or(vec![8, 1, 2], 2));
+    }
+}
diff --git a/src/problem/p2711_difference_of_number_of_distinct_values_on_diagonals.rs b/src/problem/p2711_difference_of_number_of_distinct_values_on_diagonals.rs
new file mode 100644
index 0000000..5cc4e9f
--- /dev/null
+++ b/src/problem/p2711_difference_of_number_of_distinct_values_on_diagonals.rs
@@ -0,0 +1,95 @@
+/**
+ * [2711] Difference of Number of Distinct Values on Diagonals
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn difference_of_distinct_values(grid: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
+        let m = grid.len();
+        let n = grid[0].len();
+        let mut result = vec![vec![0; n]; m];
+
+        Self::iterate_diagonal(&grid, &mut result, (0..m).rev().map(|i| (i, 0)));
+        Self::iterate_diagonal(&grid, &mut result, (0..n).rev().map(|i| (0, i)));
+
+        result
+    }
+
+    fn iterate_diagonal<T>(grid: &Vec<Vec<i32>>, result: &mut Vec<Vec<i32>>, iter: T)
+    where
+        T: Iterator<Item = (usize, usize)>,
+    {
+        let m = grid.len();
+        let n = grid[0].len();
+        let max_length = m.min(n);
+
+        let mut length = 1;
+        for (i, j) in iter {
+            let mut left_set = HashSet::with_capacity(length);
+            // 右下对角线因为涉及到添加和删除
+            // 使用哈希表存储对应数字的出现次数
+            let mut right_set = HashMap::with_capacity(length);
+
+            // 首先遍历右下
+            let (mut x, mut y) = (i + 1, j + 1);
+
+            for _ in 1..length {
+                let entry = right_set.entry(grid[x][y]).or_insert(0);
+                *entry += 1;
+
+                x += 1;
+                y += 1;
+            }
+
+            // 然后开始遍历
+            let (mut x, mut y) = (i, j);
+
+            for k in 0..length {
+                // 删除右下对角线
+                if k != 0 {
+                    let entry = right_set.get_mut(&grid[x][y]).unwrap();
+                    *entry -= 1;
+                    if *entry == 0 {
+                        right_set.remove(&grid[x][y]);
+                    }
+                }
+
+                result[x][y] = left_set.len().abs_diff(right_set.len()) as i32;
+
+                // 插入左上对角线
+                left_set.insert(grid[x][y]);
+                x += 1;
+                y += 1;
+            }
+
+            length = max_length.min(length + 1);
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2711() {
+        assert_eq!(
+            vec![vec![1, 1, 0], vec![1, 0, 1], vec![0, 1, 1]],
+            Solution::difference_of_distinct_values(vec![
+                vec![1, 2, 3],
+                vec![3, 1, 5],
+                vec![3, 2, 1]
+            ])
+        );
+        assert_eq!(
+            vec![vec![0]],
+            Solution::difference_of_distinct_values(vec![vec![1]])
+        );
+    }
+}
diff --git a/src/problem/p2712_minimum_cost_to_make_all_characters_equal.rs b/src/problem/p2712_minimum_cost_to_make_all_characters_equal.rs
new file mode 100644
index 0000000..496739c
--- /dev/null
+++ b/src/problem/p2712_minimum_cost_to_make_all_characters_equal.rs
@@ -0,0 +1,34 @@
+/**
+ * [2712] Minimum Cost to Make All Characters Equal
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn minimum_cost(s: String) -> i64 {
+        let mut result = 0;
+        let s: Vec<u8> = s.bytes().collect();
+
+        for i in 1..s.len() {
+            if s[i] != s[i - 1] {
+                result += i.min(s.len() - i) as i64;
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2712() {
+        assert_eq!(2, Solution::minimum_cost("0011".to_owned()));
+        assert_eq!(9, Solution::minimum_cost("010101".to_owned()));
+    }
+}
diff --git a/src/problem/p2716_minimize_string_length.rs b/src/problem/p2716_minimize_string_length.rs
new file mode 100644
index 0000000..acfe9b3
--- /dev/null
+++ b/src/problem/p2716_minimize_string_length.rs
@@ -0,0 +1,30 @@
+/**
+ * [2716] Minimize String Length
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashSet;
+use std::iter::FromIterator;
+
+impl Solution {
+    pub fn minimized_string_length(s: String) -> i32 {
+        let set: HashSet<u8> = HashSet::from_iter(s.bytes());
+
+        set.len() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2716() {
+        assert_eq!(3, Solution::minimized_string_length("aaabc".to_owned()));
+        assert_eq!(3, Solution::minimized_string_length("cbbd".to_owned()));
+        assert_eq!(2, Solution::minimized_string_length("dddaaa".to_owned()));
+    }
+}
diff --git a/src/problem/p2829_determine_the_minimum_sum_of_a_k_avoiding_array.rs b/src/problem/p2829_determine_the_minimum_sum_of_a_k_avoiding_array.rs
new file mode 100644
index 0000000..d27344d
--- /dev/null
+++ b/src/problem/p2829_determine_the_minimum_sum_of_a_k_avoiding_array.rs
@@ -0,0 +1,43 @@
+/**
+ * [2829] Determine the Minimum Sum of a k-avoiding Array
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn minimum_sum(n: i32, k: i32) -> i32 {
+        let mut avoid_set = HashSet::new();
+
+        let mut result = 0;
+        let mut num = 1;
+
+        for _ in 0..n {
+            while avoid_set.contains(&num) {
+                num += 1;
+            }
+
+            result += num;
+            if k - num > 0 {
+                avoid_set.insert(k - num);
+            }
+            num += 1;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2829() {
+        assert_eq!(18, Solution::minimum_sum(5, 4));
+        assert_eq!(3, Solution::minimum_sum(2, 6));
+    }
+}
diff --git a/src/problem/p2843_count_symmetric_integers.rs b/src/problem/p2843_count_symmetric_integers.rs
new file mode 100644
index 0000000..6789533
--- /dev/null
+++ b/src/problem/p2843_count_symmetric_integers.rs
@@ -0,0 +1,42 @@
+/**
+ * [2843]   Count Symmetric Integers
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_symmetric_integers(low: i32, high: i32) -> i32 {
+        // 10 -> 99 1000 -> 9999
+        (low..=high)
+            .filter_map(|i| {
+                if i >= 10 && i <= 99 {
+                    if i / 10 == i % 10 {
+                        return Some(());
+                    }
+                }
+
+                if i >= 1000 && i <= 9999 {
+                    if i / 1000 + (i / 100) % 10 == (i / 10) % 10 + i % 10 {
+                        return Some(());
+                    }
+                }
+
+                None
+            })
+            .count() as i32
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2843() {
+        assert_eq!(9, Solution::count_symmetric_integers(1, 99));
+        assert_eq!(4, Solution::count_symmetric_integers(1200, 1230));
+    }
+}
diff --git a/src/problem/p2845_count_of_interesting_subarrays.rs b/src/problem/p2845_count_of_interesting_subarrays.rs
new file mode 100644
index 0000000..d66fc25
--- /dev/null
+++ b/src/problem/p2845_count_of_interesting_subarrays.rs
@@ -0,0 +1,53 @@
+/**
+ * [2845] Count of Interesting Subarrays
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn count_interesting_subarrays(nums: Vec<i32>, modulo: i32, k: i32) -> i64 {
+        let n = nums.len();
+        let mut count = vec![0; n + 1];
+        for (i, &v) in nums.iter().enumerate() {
+            count[i + 1] = count[i] + if v % modulo == k { 1 } else { 0 };
+        }
+
+        let mut map = HashMap::new();
+        let mut result = 0;
+
+        // 类似于两数之和
+        for i in 0..=n {
+            let target = (count[i] + modulo - k) % modulo;
+
+            if let Some(&v) = map.get(&target) {
+                result += v;
+            }
+
+            let entry = map.entry(count[i] % modulo).or_insert(0);
+            *entry += 1;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2845() {
+        assert_eq!(
+            3,
+            Solution::count_interesting_subarrays(vec![3, 2, 4], 2, 1)
+        );
+        assert_eq!(
+            2,
+            Solution::count_interesting_subarrays(vec![3, 1, 9, 6], 3, 0)
+        );
+    }
+}
diff --git a/src/problem/p2873_maximum_value_of_an_ordered_triplet_i.rs b/src/problem/p2873_maximum_value_of_an_ordered_triplet_i.rs
new file mode 100644
index 0000000..3ae4ef0
--- /dev/null
+++ b/src/problem/p2873_maximum_value_of_an_ordered_triplet_i.rs
@@ -0,0 +1,39 @@
+/**
+ * [2873] Maximum Value of an Ordered Triplet I
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn maximum_triplet_value(nums: Vec<i32>) -> i64 {
+        let nums: Vec<i64> = nums.into_iter().map(|x| x as i64).collect();
+
+        let mut result = 0;
+        let n = nums.len();
+
+        for i in 0..n {
+            for j in i + 1..n {
+                for k in j + 1..n {
+                    result = result.max((nums[i] - nums[j]) * nums[k])
+                }
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2873() {
+        assert_eq!(77, Solution::maximum_triplet_value(vec![12, 6, 1, 2, 7]));
+        assert_eq!(133, Solution::maximum_triplet_value(vec![1, 10, 3, 4, 19]));
+        assert_eq!(0, Solution::maximum_triplet_value(vec![1, 2, 3]));
+    }
+}
diff --git a/src/problem/p2874_maximum_value_of_an_ordered_triplet_ii.rs b/src/problem/p2874_maximum_value_of_an_ordered_triplet_ii.rs
new file mode 100644
index 0000000..b2c8e0a
--- /dev/null
+++ b/src/problem/p2874_maximum_value_of_an_ordered_triplet_ii.rs
@@ -0,0 +1,47 @@
+/**
+ * [2874] Maximum Value of an Ordered Triplet II
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn maximum_triplet_value(nums: Vec<i32>) -> i64 {
+        let nums: Vec<i64> = nums.into_iter().map(|x| x as i64).collect();
+        let n = nums.len();
+        // max num from nums[0] to nums[i]
+        let mut prefix = vec![0; n];
+        // max num from nums[i] to nums[n - 1]
+        let mut suffix = vec![0; n];
+
+        prefix[0] = nums[0];
+        suffix[n - 1] = nums[n - 1];
+
+        for i in 1..n {
+            prefix[i] = nums[i].max(prefix[i - 1]);
+            suffix[n - i - 1] = nums[n - i - 1].max(suffix[n - i]);
+        }
+
+        let mut result = 0;
+
+        for j in 1..n - 1 {
+            result = result.max((prefix[j - 1] - nums[j]) * suffix[j + 1]);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2874() {
+        assert_eq!(77, Solution::maximum_triplet_value(vec![12, 6, 1, 2, 7]));
+        assert_eq!(133, Solution::maximum_triplet_value(vec![1, 10, 3, 4, 19]));
+        assert_eq!(0, Solution::maximum_triplet_value(vec![1, 2, 3]));
+    }
+}
diff --git a/src/problem/p2999_count_the_number_of_powerful_integers.rs b/src/problem/p2999_count_the_number_of_powerful_integers.rs
new file mode 100644
index 0000000..17b6c43
--- /dev/null
+++ b/src/problem/p2999_count_the_number_of_powerful_integers.rs
@@ -0,0 +1,111 @@
+/**
+ * [2999] Count the Number of Powerful Integers
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::str::FromStr;
+
+struct Searcher {
+    low: Vec<u8>,
+    high: Vec<u8>,
+    suffix: Vec<u8>,
+    memory: Vec<i64>,
+    limit: u8,
+}
+
+impl Searcher {
+    fn new(start: i64, finish: i64, limit: i32, s: String) -> Self {
+        let mut low: Vec<u8> = start.to_string().bytes().map(|x| x - b'0').collect();
+        let high: Vec<u8> = finish.to_string().bytes().map(|x| x - b'0').collect();
+
+        // 对齐low和high的数位
+        for _ in 0..high.len() - low.len() {
+            low.insert(0, 0);
+        }
+
+        let suffix = s.bytes().map(|x| x - b'0').collect();
+        let n = high.len();
+
+        Self {
+            low,
+            high,
+            suffix,
+            memory: vec![-1; n],
+            limit: limit as u8,
+        }
+    }
+
+    fn search(&mut self, i: usize, limit_low: bool, limit_high: bool) -> i64 {
+        if i == self.low.len() {
+            return 1;
+        }
+
+        if !limit_low && !limit_high && self.memory[i] != -1 {
+            return self.memory[i];
+        }
+
+        let low = if limit_low { self.low[i] } else { 0 };
+
+        let high = if limit_high { self.high[i] } else { 9 };
+
+        let mut result = 0;
+
+        let prefix_len = self.low.len() - self.suffix.len();
+        if i < prefix_len {
+            for digit in low..=high.min(self.limit) {
+                result += self.search(
+                    i + 1,
+                    limit_low && digit == low,
+                    limit_high && digit == high,
+                );
+            }
+        } else {
+            let digit = self.suffix[i - prefix_len];
+            if digit >= low && digit <= high.min(self.limit) {
+                result = self.search(
+                    i + 1,
+                    limit_low && digit == low,
+                    limit_high && digit == high,
+                );
+            }
+        }
+
+        if !limit_low && !limit_high {
+            self.memory[i] = result;
+        }
+
+        result
+    }
+}
+
+impl Solution {
+    pub fn number_of_powerful_int(start: i64, finish: i64, limit: i32, s: String) -> i64 {
+        let mut searcher = Searcher::new(start, finish, limit, s);
+
+        searcher.search(0, true, true)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2999() {
+        assert_eq!(
+            5,
+            Solution::number_of_powerful_int(1, 6000, 4, "123".to_owned())
+        );
+        assert_eq!(
+            2,
+            Solution::number_of_powerful_int(15, 215, 6, "10".to_owned())
+        );
+        assert_eq!(
+            0,
+            Solution::number_of_powerful_int(1000, 2000, 4, "3000".to_owned())
+        );
+    }
+}
diff --git a/src/problem/p3110_score_of_a_string.rs b/src/problem/p3110_score_of_a_string.rs
new file mode 100644
index 0000000..4bf6921
--- /dev/null
+++ b/src/problem/p3110_score_of_a_string.rs
@@ -0,0 +1,28 @@
+/**
+ * [3110] Score of a String
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn score_of_string(s: String) -> i32 {
+        s.bytes()
+            .zip(s.bytes().skip(1))
+            .map(|(first, second)| first.abs_diff(second) as i32)
+            .sum::<i32>()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3110() {
+        assert_eq!(13, Solution::score_of_string("hello".to_owned()));
+        assert_eq!(50, Solution::score_of_string("zaz".to_owned()));
+    }
+}
diff --git a/src/problem/p3272_find_the_count_of_good_integers.rs b/src/problem/p3272_find_the_count_of_good_integers.rs
new file mode 100644
index 0000000..35b3b53
--- /dev/null
+++ b/src/problem/p3272_find_the_count_of_good_integers.rs
@@ -0,0 +1,81 @@
+/**
+ * [3272] Find the Count of Good Integers
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn count_good_integers(n: i32, k: i32) -> i64 {
+        let n = n as usize;
+        let k = k as i64;
+        let base_value = 10i64.pow((n as u32 - 1) / 2);
+        let length = (n + 1) / 2;
+        let mut dict = HashSet::new();
+
+        // 枚举n个数位的回文数
+        for mut i in base_value..base_value * 10 {
+            let mut s = Vec::with_capacity(length);
+
+            while i != 0 {
+                s.push(i % 10);
+                i = i / 10;
+            }
+
+            // 这里拼接回文字符串有点困难
+            // 因为上面存数字字符存的是倒序
+            // 即 123 -> 3 2 1
+            // 所以 12321 -> 1 2 3 2 1
+            let mut real_str: Vec<i64> = s
+                .iter()
+                .rev()
+                .chain(s.iter().skip(n & 1))
+                .map(|x| *x)
+                .collect();
+
+            let number = real_str.iter().fold(0, |v, i| v * 10 + *i);
+            if number % k == 0 {
+                real_str.sort_unstable();
+                dict.insert(real_str);
+            }
+        }
+
+        let mut factorial = Vec::with_capacity(n + 1);
+        factorial.push(1);
+        for i in 1..=n {
+            factorial.push(factorial[i - 1] * i as i64);
+        }
+
+        let mut result = 0;
+
+        for str in dict.into_iter() {
+            let mut counts = [0; 10];
+            for i in str {
+                counts[i as usize] += 1;
+            }
+
+            let mut total = (n - counts[0]) as i64 * factorial[n - 1];
+            for x in counts {
+                total /= factorial[x]
+            }
+            result += total;
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3272() {
+        assert_eq!(27, Solution::count_good_integers(3, 5));
+        assert_eq!(2, Solution::count_good_integers(1, 4));
+        assert_eq!(2468, Solution::count_good_integers(5, 6));
+    }
+}
diff --git a/src/problem/p3305_count_of_substrings_containing_every_vowel_and_k_consonants_i.rs b/src/problem/p3305_count_of_substrings_containing_every_vowel_and_k_consonants_i.rs
new file mode 100644
index 0000000..458d327
--- /dev/null
+++ b/src/problem/p3305_count_of_substrings_containing_every_vowel_and_k_consonants_i.rs
@@ -0,0 +1,71 @@
+/**
+ * [3305] Count of Substrings Containing Every Vowel and K Consonants I
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::{HashMap, HashSet};
+
+impl Solution {
+    pub fn count_of_substrings(word: String, k: i32) -> i32 {
+        let word: Vec<char> = word.chars().collect();
+        let vowel_set = HashSet::from(['a', 'e', 'i', 'o', 'u']);
+
+        let count = |m| -> i32 {
+            let mut consonants = 0;
+            let mut result = 0;
+            let mut occurence = HashMap::new();
+
+            let mut right = 0;
+            for left in 0..word.len() {
+                while right < word.len() && (consonants < m || occurence.len() < vowel_set.len()) {
+                    if vowel_set.contains(&word[right]) {
+                        let entry = occurence.entry(word[right]).or_insert(0);
+                        *entry += 1;
+                    } else {
+                        consonants += 1;
+                    }
+                    right += 1;
+                }
+
+                if consonants >= m && occurence.len() == vowel_set.len() {
+                    result += (word.len() - right + 1) as i32;
+                }
+
+                if vowel_set.contains(&word[left]) {
+                    let v = occurence.get_mut(&word[left]).unwrap();
+                    *v -= 1;
+                    if *v == 0 {
+                        occurence.remove(&word[left]);
+                    }
+                } else {
+                    consonants -= 1;
+                }
+            }
+
+            result
+        };
+
+        count(k) - count(k + 1)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3305() {
+        assert_eq!(3, Solution::count_of_substrings("auieoui".to_owned(), 0));
+        assert_eq!(2, Solution::count_of_substrings("ieiaoud".to_owned(), 0));
+        assert_eq!(3, Solution::count_of_substrings("iqeaouqi".to_owned(), 2));
+        assert_eq!(
+            3,
+            Solution::count_of_substrings("ieaouqqieaouqq".to_owned(), 1)
+        );
+        assert_eq!(0, Solution::count_of_substrings("aeioqq".to_owned(), 1));
+        assert_eq!(1, Solution::count_of_substrings("aeiou".to_owned(), 0));
+    }
+}
diff --git a/src/problem/p3306_count_of_substrings_containing_every_vowel_and_k_consonants_ii.rs b/src/problem/p3306_count_of_substrings_containing_every_vowel_and_k_consonants_ii.rs
new file mode 100644
index 0000000..ef5604f
--- /dev/null
+++ b/src/problem/p3306_count_of_substrings_containing_every_vowel_and_k_consonants_ii.rs
@@ -0,0 +1,63 @@
+/**
+ * [3306] Count of Substrings Containing Every Vowel and K Consonants II
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::{HashMap, HashSet};
+
+impl Solution {
+    pub fn count_of_substrings(word: String, k: i32) -> i64 {
+        let word: Vec<char> = word.chars().collect();
+        let vowel_set = HashSet::from(['a', 'e', 'i', 'o', 'u']);
+
+        let count = |m| -> i64 {
+            let mut consonants = 0;
+            let mut result = 0;
+            let mut occurence = HashMap::new();
+
+            let mut right = 0;
+            for left in 0..word.len() {
+                while right < word.len() && (consonants < m || occurence.len() < vowel_set.len()) {
+                    if vowel_set.contains(&word[right]) {
+                        let entry = occurence.entry(word[right]).or_insert(0i64);
+                        *entry += 1;
+                    } else {
+                        consonants += 1;
+                    }
+                    right += 1;
+                }
+
+                if consonants >= m && occurence.len() == vowel_set.len() {
+                    result += (word.len() - right + 1) as i64;
+                }
+
+                if vowel_set.contains(&word[left]) {
+                    let v = occurence.get_mut(&word[left]).unwrap();
+                    *v -= 1;
+                    if *v == 0 {
+                        occurence.remove(&word[left]);
+                    }
+                } else {
+                    consonants -= 1;
+                }
+            }
+
+            result
+        };
+
+        count(k) - count(k + 1)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3306() {
+        assert_eq!(0, Solution::count_of_substrings("aeioqq".to_owned(), 1));
+    }
+}
diff --git a/src/problem/p3340_check_balanced_string.rs b/src/problem/p3340_check_balanced_string.rs
new file mode 100644
index 0000000..cbc54e7
--- /dev/null
+++ b/src/problem/p3340_check_balanced_string.rs
@@ -0,0 +1,27 @@
+/**
+ * [3340] Check Balanced String
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn is_balanced(num: String) -> bool {
+        let num: Vec<i32> = num.bytes().map(|x| (x - b'0') as i32).collect();
+
+        num.iter().step_by(2).sum::<i32>() == num.iter().skip(1).step_by(2).sum::<i32>()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3340() {
+        assert!(!Solution::is_balanced("1234".to_owned()));
+        assert!(Solution::is_balanced("24123".to_owned()));
+    }
+}
diff --git a/src/problem/p3375_minimum_operations_to_make_array_values_equal_to_k.rs b/src/problem/p3375_minimum_operations_to_make_array_values_equal_to_k.rs
new file mode 100644
index 0000000..5c7dd70
--- /dev/null
+++ b/src/problem/p3375_minimum_operations_to_make_array_values_equal_to_k.rs
@@ -0,0 +1,41 @@
+/**
+ * [3375] Minimum Operations to Make Array Values Equal to K
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn min_operations(nums: Vec<i32>, k: i32) -> i32 {
+        let set: HashSet<i32> = nums.into_iter().collect();
+
+        let mut result = 0;
+
+        for &i in set.iter() {
+            if i < k {
+                return -1;
+            }
+
+            if i > k {
+                result += 1;
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3375() {
+        assert_eq!(2, Solution::min_operations(vec![5, 2, 5, 4, 5], 2));
+        assert_eq!(-1, Solution::min_operations(vec![2, 1, 2], 2));
+        assert_eq!(4, Solution::min_operations(vec![9, 7, 5, 3], 1));
+    }
+}
diff --git a/src/problem/p3396_minimum_number_of_operations_to_make_elements_in_array_distinct.rs b/src/problem/p3396_minimum_number_of_operations_to_make_elements_in_array_distinct.rs
new file mode 100644
index 0000000..121a003
--- /dev/null
+++ b/src/problem/p3396_minimum_number_of_operations_to_make_elements_in_array_distinct.rs
@@ -0,0 +1,57 @@
+/**
+ * [3396] Minimum Number of Operations to Make Elements in Array Distinct
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn minimum_operations(nums: Vec<i32>) -> i32 {
+        let mut map = HashMap::new();
+
+        for &i in nums.iter() {
+            let mut entry = map.entry(i).or_insert(0);
+            *entry += 1;
+        }
+
+        let mut result = 0;
+        let mut pos = 0;
+
+        while pos < nums.len() {
+            if map.values().all(|i| *i == 1) {
+                break;
+            }
+
+            for p in pos..(pos + 3).min(nums.len()) {
+                pos = p;
+                let value = map.get_mut(&nums[pos]).unwrap();
+                *value -= 1;
+            }
+            pos += 1;
+
+            result += 1;
+            map.retain(|_, v| *v != 0);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3396() {
+        assert_eq!(2, Solution::minimum_operations(vec![5, 7, 11, 12, 12]));
+        assert_eq!(
+            2,
+            Solution::minimum_operations(vec![1, 2, 3, 4, 2, 3, 3, 5, 7])
+        );
+        assert_eq!(2, Solution::minimum_operations(vec![4, 5, 6, 4, 4]));
+        assert_eq!(0, Solution::minimum_operations(vec![6, 7, 8, 9]));
+    }
+}
diff --git a/src/problem/p368_largest_divisible_subset.rs b/src/problem/p368_largest_divisible_subset.rs
new file mode 100644
index 0000000..2748396
--- /dev/null
+++ b/src/problem/p368_largest_divisible_subset.rs
@@ -0,0 +1,72 @@
+/**
+ * [368] Largest Divisible Subset
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn largest_divisible_subset(mut nums: Vec<i32>) -> Vec<i32> {
+        nums.sort_unstable();
+        let n = nums.len();
+
+        let mut dp = vec![1; n];
+        let mut max_size = 1;
+        let mut max_value = nums[0];
+
+        for i in 1..n {
+            for j in 0..i {
+                if nums[i] % nums[j] == 0 {
+                    dp[i] = dp[i].max(dp[j] + 1);
+                }
+            }
+
+            if dp[i] > max_size {
+                max_size = dp[i];
+                max_value = nums[i];
+            }
+        }
+
+        // 获得求得的最大子集
+        let mut result = vec![];
+
+        if max_size == 1 {
+            result.push(nums[0]);
+            return result;
+        }
+
+        for i in (0..n).rev() {
+            if dp[i] == max_size && max_value % nums[i] == 0 {
+                result.push(nums[i]);
+                max_value = nums[i];
+                max_size -= 1;
+            }
+
+            if max_size <= 0 {
+                break;
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_368() {
+        assert_array_unorder_equal!(vec![1], Solution::largest_divisible_subset(vec![1]));
+        assert_array_unorder_equal!(
+            vec![1, 2],
+            Solution::largest_divisible_subset(vec![1, 2, 3])
+        );
+        assert_array_unorder_equal!(
+            vec![1, 2, 4, 8],
+            Solution::largest_divisible_subset(vec![1, 2, 4, 8])
+        );
+    }
+}
diff --git a/src/problem/p416_partition_equal_subset_sum.rs b/src/problem/p416_partition_equal_subset_sum.rs
new file mode 100644
index 0000000..bac94e1
--- /dev/null
+++ b/src/problem/p416_partition_equal_subset_sum.rs
@@ -0,0 +1,58 @@
+/**
+ * [416] Partition Equal Subset Sum
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn can_partition(nums: Vec<i32>) -> bool {
+        let n = nums.len();
+        if n < 2 {
+            return false;
+        }
+
+        let nums: Vec<usize> = nums.into_iter().map(|x| x as usize).collect();
+        let sum: usize = nums.iter().sum();
+
+        if sum % 2 != 0 {
+            return false;
+        }
+
+        let middle = sum / 2;
+        let mut dp = vec![vec![false; middle + 1]; n];
+
+        // 初始化dp
+        for i in 0..n {
+            dp[i][0] = true;
+        }
+        if nums[0] <= middle {
+            dp[0][nums[0]] = true;
+        }
+
+        for i in 1..n {
+            for j in 1..=middle {
+                if j < nums[i] {
+                    dp[i][j] = dp[i - 1][j];
+                } else {
+                    dp[i][j] = dp[i - 1][j] || dp[i - 1][j - nums[i]];
+                }
+            }
+        }
+
+        dp[n - 1][middle]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_416() {
+        assert!(Solution::can_partition(vec![1, 5, 11, 5]));
+        assert!(!Solution::can_partition(vec![1, 2, 3, 5]));
+    }
+}
diff --git a/src/problem/p624_maximum_distance_in_arrays.rs b/src/problem/p624_maximum_distance_in_arrays.rs
new file mode 100644
index 0000000..50c59a9
--- /dev/null
+++ b/src/problem/p624_maximum_distance_in_arrays.rs
@@ -0,0 +1,43 @@
+use std::thread::available_parallelism;
+
+/**
+ * [624] Maximum Distance in Arrays
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn max_distance(arrays: Vec<Vec<i32>>) -> i32 {
+        let mut result = 0;
+        // -10e4 <= array[i][j] <= 10e4
+        let (mut min, mut max) = (10_000 + 1, -10_000 - 1);
+
+        for array in arrays {
+            result = result
+                .max(*array.last().unwrap() - min)
+                .max(max - *array.first().unwrap());
+
+            min = min.min(*array.first().unwrap());
+            max = max.max(*array.last().unwrap());
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_624() {
+        assert_eq!(
+            4,
+            Solution::max_distance(vec![vec![1, 2, 3], vec![4, 5], vec![1, 2, 3]])
+        );
+        assert_eq!(0, Solution::max_distance(vec![vec![1], vec![1]]));
+    }
+}
diff --git a/src/problem/p781_rabbits_in_forest.rs b/src/problem/p781_rabbits_in_forest.rs
new file mode 100644
index 0000000..e521e3e
--- /dev/null
+++ b/src/problem/p781_rabbits_in_forest.rs
@@ -0,0 +1,46 @@
+/**
+ * [781] Rabbits in Forest
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn num_rabbits(answers: Vec<i32>) -> i32 {
+        let mut map = HashMap::new();
+
+        for i in answers.into_iter() {
+            let entry = map.entry(i).or_insert(0);
+            *entry += 1;
+        }
+
+        let mut result = 0;
+
+        for (k, mut v) in map.into_iter() {
+            // 同种颜色兔子最多有k + 1个
+            let max_count = k + 1;
+
+            while v > 0 {
+                result += max_count;
+                v -= max_count;
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_781() {
+        assert_eq!(5, Solution::num_rabbits(vec![1, 0, 1, 0, 0]));
+        assert_eq!(5, Solution::num_rabbits(vec![1, 1, 2]));
+        assert_eq!(11, Solution::num_rabbits(vec![10, 10, 10]))
+    }
+}
diff --git a/src/util/mod.rs b/src/util/mod.rs
index 5a3e574..393b4ec 100644
--- a/src/util/mod.rs
+++ b/src/util/mod.rs
@@ -6,3 +6,5 @@ pub mod vec_string;
 pub mod tree;
 #[macro_use]
 pub mod point;
+#[macro_use]
+pub mod vec_equal;
diff --git a/src/util/vec_equal.rs b/src/util/vec_equal.rs
new file mode 100644
index 0000000..b84fc69
--- /dev/null
+++ b/src/util/vec_equal.rs
@@ -0,0 +1,51 @@
+use std::collections::HashSet;
+use std::hash::Hash;
+use std::iter::FromIterator;
+
+pub fn assert_array_unorder_equal<T>(a: &Vec<T>, b: &Vec<T>)
+where
+    T: Eq,
+    T: Hash,
+{
+    assert_eq!(a.len(), b.len());
+
+    let set: HashSet<&T> = HashSet::from_iter(a.into_iter());
+
+    for i in b.iter() {
+        assert!(set.contains(i));
+    }
+}
+
+#[macro_export]
+macro_rules! assert_array_unorder_equal {
+    ($left:expr, $right:expr $(,)?) => {
+        match (&$left, &$right) {
+            (left_value, right_value) => {
+                $crate::util::vec_equal::assert_array_unorder_equal(left_value, right_value);
+            }
+        }
+    };
+}
+
+pub fn assert_inner_array_unorder_equal<T>(a: &Vec<Vec<T>>, b: &Vec<Vec<T>>)
+where
+    T: Eq,
+    T: Hash,
+{
+    assert_eq!(a.len(), b.len());
+
+    for (i, j) in a.iter().zip(b.iter()) {
+        assert_array_unorder_equal(i, j);
+    }
+}
+
+#[macro_export]
+macro_rules! assert_inner_array_unorder_equal {
+    ($left:expr, $right:expr $(,)?) => {
+        match (&$left, &$right) {
+            (left_value, right_value) => {
+                $crate::util::vec_equal::assert_inner_array_unorder_equal(left_value, right_value);
+            }
+        }
+    };
+}