20250416 finished.

src/problem/mod.rs

@@ -601,3 +601,5 @@ 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;

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));
+    }
+}