两数之和|博客系列

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    for (let i = 0; i < nums.length; i++) {
        for (let j = i + 1; j < nums.length; j++) {
            if (nums[i] + nums[j] === target) {
                return [i, j]
            }
        }
    }
};

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    const map = {} // 定义一个空的对象
    const len = nums.length
    for (let i = 0; i < len; i++) {
        const targetNum = target - nums[i]
        if (targetNum in map) return [map[targetNum], i]
        map[nums[i]] = i
    }
};