Two Sum

class Solution {public:    vector<int> twoSum(vector<int>& nums, int target) {        unordered_map<int, int> m;        vector<int> res;        for(int i = 0; i < nums.size(); i++){            m[nums[i]] = i+1;        }        for(int i = 0; i < nums.size(); i++){            int gap = target - nums[i];            if(m.find(gap)!=m.end() && m[gap]!=i+1){                res.push_back(i+1);                res.push_back(m[gap]);                return res;            }        }        return res;    }};