#2225 - Find Players With Zero or One Losses

Problem Description

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.

Solution

/**
 * @param {number[][]} matches
 * @return {number[][]}
 */
var findWinners = function(matches) {
  const lossCount = new Map();

  for (const [winner, loser] of matches) {
    lossCount.set(winner, lossCount.get(winner) || 0);
    lossCount.set(loser, (lossCount.get(loser) || 0) + 1);
  }

  const noLosses = [];
  const oneLoss = [];

  for (const [player, losses] of lossCount) {
    if (losses === 0) noLosses.push(player);
    else if (losses === 1) oneLoss.push(player);
  }

  return [
    noLosses.sort((a, b) => a - b),
    oneLoss.sort((a, b) => a - b)
  ];
};