Find Players With Zero or One Losses — Python

# Time:  O(nlogn)
# Space: O(n)

import collections


# hash, sort
class Solution(object):
    def findWinners(self, matches):
        """
        :type matches: List[List[int]]
        :rtype: List[List[int]]
        """
        lose = collections.defaultdict(int)
        players_set = set()
        for x, y in matches:
            lose[y] += 1
            players_set.add(x)
            players_set.add(y)
        return [[x for x in sorted(players_set) if lose[x] == i] for i in xrange(2)]