diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 9f09686..0e3b7de 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -613,3 +613,6 @@ 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;
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/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));
+    }
+}