Leetcode 1, Two Sum

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

（给定一个整数数组，返回两个数的下标，它们之和等于一个给定的数)

You may assume that each input would have exactly one solution.（你可以假设对每一个输入都有一个确定的答案）

Example:

Given nums = [2, 7, 11, 15], target = 9,Because nums[0] + nums[1] = 2 + 7 = 9,return [0, 1].

</pre><pre name="code" class="cpp">class Solution {public:    vector<int> twoSum(vector<int>& nums, int target) {        vector<int> vec;        for(int i=0;i<nums.size()-1;i++)        {                for(int j=i+1;j<nums.size();j++)                {                        if(nums[i]+nums[j]==target)                        {                                vec.push_back(i);                                vec.push_back(j);                                return vec;                        }                }        }        return vec;    }};