_921. Minimum Add to Make Parentheses Valid.md

921. Minimum Add to Make Parentheses Valid

All prompts are owned by LeetCode. To view the prompt, click the title link above.

Back to top

---

First completed : June 12, 2024

Last updated : July 01, 2024

---

Related Topics : String, Stack, Greedy

Acceptance Rate : 74.61 %

---

Solutions

• m921.java
• m921.py

Java

m921.java

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

        int counter = 0;
        for (Character c : s.toCharArray()) {
            if (c == '(') {
                stk.push(true);
            } else if (stk.size() > 0 && stk.peek()) {
                stk.pop();
            } else {
                counter++;
            }
        }
        counter += stk.size();
        return counter;
    }
}

Python

m921.py

class Solution:
    def minAddToMakeValid(self, s: str) -> int:
        brackets = []
        counter = 0
        for c in s :
            if c == '(' :
                brackets.append(True)
            elif len(brackets) > 0 and brackets[-1] :
                brackets.pop()
            else :
                counter += 1
        counter += len(brackets)
        
        return counter