20250316 finished.

src/problem/mod.rs

@@ -540,3 +540,5 @@ 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;

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()));
+    }
+}