5.15

394. 字符串解码

/**
 * @param {string} s
 * @return {string}
 */
 // 用栈解决
var decodeString = function(s) {
    var res = ''
    var stack = []
    var multi = 0
    for (let i of s) {
        if (i === '[') {
            stack.push([multi, res])
            res = ''
            multi = 0
        } else if (i === ']') {
            const [currentMulti, lastRes] =  stack.pop()
            res = lastRes + currentMulti * res
        } else if ('0' <= i <= '9') {
            multi = multi * 10 + ~~i
        } else {
            res += i
        }
    }
    return res
};

162. 寻找峰值

寻找最大值

/**
 * @param {number[]} nums
 * @return {number}
 */
var findPeakElement = function(nums) {
    let idx = 0;
    for (let i = 1; i < nums.length; ++i) {
        if (nums[i] > nums[idx]) {
            idx = i;
        }
    }
    return idx;
};