Leetcode - 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.

Example:

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

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

UPDATE (2016/2/13):

The return format had been changed to zero-based indices. Please read the above updated description carefully.

vector<int> twoSum(vector<int>& nums, int target) {
std::unordered_map<int,int> map;
vector<int> vresult;
for(int i = 0 ; i < nums.size(); i ++) {
int dif = target - nums[i];
if(map.find(dif) != map.end()) {
vresult.push_back(i);
vresult.push_back(map[dif]);
return vresult;
}
map[nums[i]] = i;
}

return vresult;
}