题解 | 有效括号序列

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param s string字符串 
     * @return bool布尔型
     */
    public boolean isValid (String s) {
        // write code here
        Stack<Character> stack = new Stack<>();
        for(Character c : s.toCharArray()){
            if(!stack.isEmpty() && stack.peek() == '[' && c == ']') stack.pop();
            else if(!stack.isEmpty() && stack.peek() == '(' && c == ')') stack.pop();
            else if(!stack.isEmpty() && stack.peek() == '{' && c == '}') stack.pop();
            else stack.push(c);
        }
        
        return (stack.isEmpty() ? true : false);
    }
}