1. Two Sum

1. Two Sum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].
题意：给定一个数组和一个目标值，找出数组中两项值相加等于目标值的索引
代码如下

var twoSum = function(nums, target) {
    let res=[];
    let obj={};
    nums.forEach((item,index)=>{
        //  如果obj中已存在值为（target-item）键，则找到了两个值相加等于target的项，返回索引即可
        if(obj.hasOwnProperty(target-item)){
            res[1]=index;
            res[0]=obj[target-item];
            return res;
        }
        // obj键存数组项的值，值存数组项的索引
        obj[item]=index;
    })
    return res;
};

1. Two Sum

原文：https://www.cnblogs.com/xingguozhiming/p/10372241.html