Today I have done leetcode's January LeetCoding Challenge with cpp.

January LeetCoding Challenge 15

Description

Find Players With Zero or One Losses

You are given an integer array matches where matches[i] = [winneri, loseri] indicates that the player winneri defeated player loseri in a match.

Return a list answer of size 2 where:

• answer[0] is a list of all players that have not lost any matches.
• answer[1] is a list of all players that have lost exactly one match.

The values in the two lists should be returned in increasing order.

Note:

• You should only consider the players that have played at least one match.
• The testcases will be generated such that no two matches will have the same outcome.

Example 1:

Input: matches = [[1,3],[2,3],[3,6],[5,6],[5,7],[4,5],[4,8],[4,9],[10,4],[10,9]]
Output: [[1,2,10],[4,5,7,8]]
Explanation:
Players 1, 2, and 10 have not lost any matches.
Players 4, 5, 7, and 8 each have lost one match.
Players 3, 6, and 9 each have lost two matches.
Thus, answer[0] = [1,2,10] and answer[1] = [4,5,7,8].

Example 2:

Input: matches = [[2,3],[1,3],[5,4],[6,4]]
Output: [[1,2,5,6],[]]
Explanation:
Players 1, 2, 5, and 6 have not lost any matches.
Players 3 and 4 each have lost two matches.
Thus, answer[0] = [1,2,5,6] and answer[1] = [].

Constraints:

• 1 <= matches.length <= 105
• matches[i].length == 2
• 1 <= winneri, loseri <= 105
• winneri != loseri
• All matches[i] are unique.

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  vector<vector<int>> findWinners(vector<vector<int>>& matches) {
    map<int, int> lost;
    for(const auto &match: matches) {
      lost[match[0]] += 0;
      lost[match[1]] += 1;
    }
    vector<vector<int>> answer(2);
    for(const auto &[player, losses] : lost) {
      if(!losses) {
        answer[0].push_back(player);
      } else if(losses == 1) {
        answer[1].push_back(player);
      }
    }
    return answer;
  }
};

// Accepted
// 127/127 cases passed (511 ms)
// Your runtime beats 62.66 % of cpp submissions
// Your memory usage beats 88.18 % of cpp submissions (162.5 MB)