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<>();

        char[] chs = s.toCharArray();

        for (int i = 0; i < chs.length; i++) {
            char a = chs[i];
            if (stack.size() > 0 && stack.peek() == a) {
                stack.pop();
            } else {
                switch (a) {
                    case '{' :
                        stack.push('}');
                        break;
                    case '[' :
                        stack.push(']');
                        break;
                    case '(' :
                        stack.push(')');
                        break;
                    default:
                        stack.push(a);
                        break;
                }
            }

        }


        return stack.isEmpty();
    }
}