s0032

src/s0032_longest_valid_parentheses.cpp

@@ -0,0 +1,18 @@
+#include "s0032_longest_valid_parentheses.hpp"
+
+int Solution::longestValidParentheses(string s) {
+  int maxans = 0, n = s.length();
+  vector<int> dp(n, 0);
+  for (int i = 1; i < n; i++) {
+    if (s[i] == ')') {
+      if (s[i - 1] == '(') {
+        dp[i] = (i >= 2 ? dp[i - 2] : 0) + 2;
+      } else if (i - dp[i - 1] > 0 && s[i - dp[i - 1] - 1] == '(') {
+        dp[i] =
+            dp[i - 1] + ((i - dp[i - 1]) >= 2 ? dp[i - dp[i - 1] - 2] : 0) + 2;
+      }
+      maxans = max(maxans, dp[i]);
+    }
+  }
+  return maxans;
+}