Create ValidParanthesis.java

Leetcode/ValidParanthesis.java

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+/**
+921. Minimum Add to Make Parentheses Valid
+Solved
+Medium
+Topics
+Companies
+A parentheses string is valid if and only if:
+
+It is the empty string,
+It can be written as AB (A concatenated with B), where A and B are valid strings, or
+It can be written as (A), where A is a valid string.
+You are given a parentheses string s. In one move, you can insert a parenthesis at any position of the string.
+
+For example, if s = "()))", you can insert an opening parenthesis to be "(()))" or a closing parenthesis to be "())))".
+Return the minimum number of moves required to make s valid.
+
+ **/
+class Solution {
+    public int minAddToMakeValid(String s) {
+        int forward =0;
+        int mismatch=0;
+        char[] b = s.toCharArray();
+        for(char a:b){
+            if(a=='(') forward++;
+            else{
+                if(forward>0) forward--;
+                else mismatch++;
+            }
+        }
+
+        return mismatch+forward;
+    }
+}