[프로그래머스] 순위

programmers.co.kr/learn/courses/30/lessons/49191

코딩테스트 연습 - 순위

from collections import defaultdict

def solution(n, results):
    answer = 0
    win = defaultdict(set)
    lose = defaultdict(set)

    for res in results:  
      win[res[0]].add(res[1])
      lose[res[1]].add(res[0])

    for i in range(1, n+1):
      for j in lose[i]:
        win[j].update(win[i])
      for k in win[i]:
        lose[k].update(lose[i])
    
    for i in range(1, n+1):
      if len(win[i]) + len(lose[i]) == n-1:
        answer += 1

    return answer