牛客题霸括号序列

import java.util.*;


public class Solution {
    public static boolean isValid (String s) {
        // write code here
        Stack<Character> stack = new Stack<>();
        for (int i = 0 ; i < s.length() ; i++){
            if (s.charAt(i) == '('){
                stack.push(')');
            }else if (s.charAt(i) == '['){
                stack.push(']');
            }else if (s.charAt(i) == '{'){
                stack.push('}');
            }else if ( stack.isEmpty() || stack.pop() != s.charAt(i)){
                return false;
            }
        }
        return stack.isEmpty();
    }
}