LeetCode1.Two Sum 两数之和

/*
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].
*/


/*
思路：
1. 构建一个对象
2. 判断对象的key中有没有target减去当前的数组值
3. 没有则把当前的数组值和位置存入对象
4. 有则取出对应的位置 
*/
var twoSum = function(nums, target){
    var map = {};
    for(var i=0; i<nums.length; i++){
        var v = nums[i];
        if(map[target-v] > -1){
            return [map[target-v], i];
        }
        else{
            map[v] = i;
        }
    }
}

console.log(twoSum([2,7,11,15], 22));