20.有效的括号-栈思路.js

/*
 * @lc app=leetcode.cn id=20 lang=javascript
 *
 * [20] 有效的括号
 */

// @lc code=start
/**
 * @param {string} s
 * @return {boolean
 */
var isValid = function (s) {
    const stack = [];
    for (let i = 0; i < s.length; i++) {
        const len = stack.length;
        switch (s[i]) {
            case "(":
            case "[":
            case "{":
                stack.push(s[i]);
                break;
            case ")":
                if (stack[len - 1] !== "(") return false;
                stack.pop();
                break;
            case "]":
                if (stack[len - 1] !== "[") return false;
                stack.pop();
                break;
            case "}":
                if (stack[len - 1] !== "{") return false;
                stack.pop();
                break;
        }
    }

    return stack.length === 0;
};
// @lc code=end