问题描述
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：用目标值减去数组中的任一个值，然后查找数组中其余的值是否有和这个差值相等的元素
JavaScript代码

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