#include "s0001_two_sum.hpp"
using namespace std;

vector<int> Solution::twoSum(vector<int>& nums, int target) {
  unordered_map<int, int> hashtable;
  for (int i = 0; i < nums.size(); ++i) {
    auto it = hashtable.find(target - nums[i]);
    if (it != hashtable.end()) {
      return {it->second, i};
    }
    hashtable[nums[i]] = i;
  }
  return {};
}