2225. Find Players With Zero or One Losses

문제)

2225. 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.

 

문제 이해)

-  위너, 루저를 분리

-  counter, set 사용

 

솔루션1)

class Solution:
    def findWinners(self, matches: List[List[int]]) -> List[List[int]]:
        # 위너, 루저 분리
        matches = (list(zip(*matches)))
        winners = matches[0]
        loser = matches[1]

        # 한 번만 패배한 루저 찾기
        loser_counter = Counter(loser)
        answer2 = [n for n, count in loser_counter.items() if count == 1]

        # 한 번도 패배하지 않은 위너 찾기
        winners = set(winners) - set(loser_counter)

        return [sorted(winners), sorted(answer2)]