diff --git a/Longest Valid Parentheses.java b/Longest Valid Parentheses.java
new file mode 100644
index 0000000..3bfc984
--- /dev/null
+++ b/Longest Valid Parentheses.java	
@@ -0,0 +1,38 @@
+class LongestValid {
+    public int longestValidParentheses(String s) {
+        if (s == null || s.length() < 2)
+            return 0;
+        int left=0, right=0, maxLen=0;
+        for(char c: s.toCharArray()){
+            if (c == '('){
+                left++;
+            }
+            else{
+                right++;
+                if (left == right)
+                    maxLen = Math.max(maxLen,2*right);
+                else if (right > left){
+                    left=0;
+                    right=0;
+                }
+            }
+        }
+        left=0;
+        right=0;
+        for (int i=s.length()-1; i>=0; --i){
+            if (s.charAt(i) == ')'){
+                right++;
+            }
+            else{
+                left++;
+                if (left == right)
+                    maxLen = Math.max(maxLen,2*left);
+                else if (left > right){
+                    left = 0;
+                    right = 0;
+                }
+            }
+        }
+        return maxLen;
+    }
+}