From 398219824493386e06160e1dce11648a176fd4f8 Mon Sep 17 00:00:00 2001
From: ShrutiAggarwal99 <31125152+ShrutiAggarwal99@users.noreply.github.com>
Date: Mon, 14 Oct 2019 21:42:41 +0530
Subject: [PATCH] Create Longest_Valid_Parenthesis.cpp

---
 .../Longest_Valid_Parenthesis.cpp             | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 DynamicProgramming/Longest_Valid_Parenthesis.cpp

diff --git a/DynamicProgramming/Longest_Valid_Parenthesis.cpp b/DynamicProgramming/Longest_Valid_Parenthesis.cpp
new file mode 100644
index 0000000..9866bdf
--- /dev/null
+++ b/DynamicProgramming/Longest_Valid_Parenthesis.cpp
@@ -0,0 +1,22 @@
+// Link to the question : https://leetcode.com/problems/longest-valid-parentheses/
+
+class Solution {
+public:
+    int longestValidParentheses(string s) {
+        int n=s.length(), maxLength=0;
+        stack<int> st;
+        st.push(-1);
+        
+        for(int i=0;i<n;i++){
+            if(s[i]=='('){
+                st.push(i);
+            }
+            else{
+                st.pop();
+                if(st.empty()) st.push(i);
+                else maxLength=max(maxLength,i-st.top());
+            }
+        }
+        return maxLength;
+    }
+};