LeetCode Challenge #921. Minimum Add to Make Parentheses Valid

Day 54 of 100 Days LeetCode Challenge

LeetCode Challenge #921. Minimum Add to Make Parentheses Valid

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.

Example 1:

Input: s = "())"
Output: 1

Example 2:

Input: s = "((("
Output: 3

Constraints:

1 <= s.length <= 1000
s[i] is either '(' or ')'.

Video Solution

Java Solution

				
					class Solution {
    public int minAddToMakeValid(String s) {
        Stack<Character> st = new Stack<>();

        int count = 0 ;

        for(int i=0;i<s.length();i++)
        {
          char ch = s.charAt(i);
          if(ch=='('){
              st.push(ch);
          }else if ( st.size()>0 && st.peek()=='('){ // closing ")"
                st.pop();  
          }else{
             count++;
             }
        }

    return st.size() + count ;
    }
}

Day 54 of 100 Days LeetCode Challenge

LeetCode Challenge #921. Minimum Add to Make Parentheses Valid

Video Solution

Java Solution

Happy Coding with edSlash

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