#include <iostream>
#include <unordered_map>
#include <vector>

using namespace std;

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
      vector<int> res(2);

      unordered_map<int, int> d;

      for (size_t i = 0; i < nums.size(); i++) {
        if (d.find(target - nums[i]) != d.end()) {
          res[0] = i;
          res[1] = d[target - nums[i]];
          return res;
        } else {
          d[nums[i]] = i;
        }
      }

      return res;
    }
};

int main (int argc, char *argv[]) {
  Solution s;
  
  vector<int> test1 = {2, 7, 11, 15}; int target1 = 9;
  vector<int> test2 = {3, 2, 4}; int target2 = 6;
  vector<int> test3 = {3, 3}; int target3 = 6;
  
  vector<int> res1 = s.twoSum(test1, target1);
  cout << res1[0] << ' ' << res1[1] << endl;
  vector<int> res2 = s.twoSum(test2, target2);
  cout << res2[0] << ' ' << res2[1] << endl;
  vector<int> res3 = s.twoSum(test3, target3);
  cout << res3[0] << ' ' << res3[1] << endl;

  return 0;
}