Submission #11197268

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Source Code Expand

import sys
input = sys.stdin.readline

n, m = map(int, input().split())
g = [[] for _ in range(n)]
d = {}
for i in range(n):
    kl = list(map(int, input().split()))
    L = kl[1:]
    L = [l-1 for l in L]
    for l in L:
        if l not in d:
            d[l] = i
        else:
            g[d[l]].append(i)
            g[i].append(d[l])

from collections import deque
s = deque()
s.append(0)
visit = [-1]*n
visit[0] = 0
while s:
    x = s.pop()
    for nx in g[x]:
        if visit[nx] == -1:
            visit[nx] = 0
            s.append(nx)
if min(visit) != -1:
    print('YES')
else:
    print('NO')

Submission Info

Judge Result