위상 정렬.py

from collections import deque

v, e = map(int,input().split())
indegree = [0] * (v+1)

graph = [[] for i in range(v+1)]

for _ in range(e):
  a,b = map(int,input().split())
  graph[a].append(b)
  indegree[b] += 1

def topology_sort():
  result = []
  q = deque()

  for i in range(1,v+1):
    if indegree[i] == 0:
      q.append(i)
  
  while q:
    now = q.popleft()
    result.append(now)
    for i in graph[now]:
      indegree[i] -= 1
      if indegree[i] == 0:
        q.append(i)
  for i in result:
    print(i,end=' ')
topology_sort()