# BOJ - 1325 - 효율적인 해킹

Updated:

```
import sys
from collections import deque
def BFS(computer, idx, N):
ret = 0
dq = deque()
dq.append(idx)
visit = [0] * (N + 1)
visit[idx] = 1
while dq:
u = dq.popleft()
ret += 1
for w in computer[u]:
if not visit[w]:
visit[w] = 1
dq.append(w)
return ret
def solution():
N, M = map(int, sys.stdin.readline().split())
computer = [[] for _ in range(N + 1)]
for i in range(M):
A, B = map(int, sys.stdin.readline().split())
computer[B].append(A)
ans = 0
ret = []
for i in range(1, N + 1):
if computer[i]:
tmp = BFS(computer, i, N)
if ans <= tmp:
if ans < tmp:
ret = []
ans = tmp
ret.append(i)
print(*ret)
solution()
```

https://www.acmicpc.net/problem/1325

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