1
class Solution {
2
 public:
3
  vector<int> findErrorNums(vector<int> &nums) {
4
    unordered_map<int, int> m;
5
    int p, q;
6
    for (auto &x : nums) {
7
      m[x]++;
8
      if (m[x] == 2) {
9
        p = x;
10
        break;
11
      }
12
    }
13
    int n = nums.size();
14
    q = (n * (n + 1)) / 2 - accumulate(nums.begin(), nums.end(), 0) + p;
15
    return {p, q};
16
  }
17
};
18
// if you like the solution plz upvote.