LeetCode Two Sum

class Solution {public:    vector<int> twoSum(vector<int>& nums, int target) {        vector<int> vec;        for(int i=0;i<nums.size();i++){            for(int j=i+1;j<nums.size();j++){                if(nums[j]==target-nums[i]){                    vec.insert(vec.begin(),i);                    vec.push_back(j);                }            }        }        return vec;    }};4、other solutions
vector<int> twoSum(vector<int> &numbers, int target){    //Key is the number and value is its index in the vector.        unordered_map<int, int> hash;        vector<int> result;        for (int i = 0; i < numbers.size(); i++) {                int numberToFind = target - numbers[i];            //if numberToFind is found in map, return them                if (hash.find(numberToFind) != hash.end()) {                    //+1 because indices are NOT zero based                        result.push_back(hash[numberToFind] + 1);                        result.push_back(i + 1);                                             return result;                }            //number was not found. Put it in the map.                hash[numbers[i]] = i;        }        return result;}