vector<int> twoSum(vector<int>& nums, int target) {
            int n = nums.size();
            unordered_map<int,int>mp;
            vector<int>v;
           for(int i=0;i<n;i++){
               if(mp.find(target-nums[i])!=mp.end()){
                   v.push_back(i);
                   v.push_back(mp[target-nums[i]]);
               }else{
                   mp[nums[i]] = i;
               }
           }
        return v;
    }