프로그래머스 - LV3. 순위

문제

https://school.programmers.co.kr/learn/courses/30/lessons/49191

프로그래머스

 

코드

defaultdict(set) 이용

from collections import defaultdict

def solution(n, results):
    answer = 0
    win = defaultdict(set)
    lose = defaultdict(set)
    
    for r in results:
        win[r[0]-1].add(r[1])
        lose[r[1]-1].add(r[0])
        
    for i in range(n):
        for loser in win[i]:
            lose[loser-1].update(lose[i])
        for winner in lose[i]:
            win[winner-1].update(win[i])
            
    for i in range(n):
        if len(win[i]) + len(lose[i]) == n-1:
            answer += 1
    
    return answer