https://school.programmers.co.kr/learn/courses/30/lessons/12909?language=java

Problem

Code

import java.util.Stack;

class Solution {
    boolean solution(String s) {
        boolean answer = true;
        Stack<Character> stack = new Stack<>();
        
        for (char ch : s.toCharArray()) {
            if (ch == '(') stack.push(ch);
            else {
                if (stack.isEmpty()) answer = false;
                else stack.pop();
            }
        }
        
        if (!stack.isEmpty()) answer = false;

        return answer;
    }
}

Result