Submission #992786

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Source Code Expand

#!/usr/bin/env python3
# -*- coding:utf-8 -*-

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

import sys

N, M = map(int, input().split())

if N > 1000 and M > 1000:
    print("YES")
    sys.exit()

L = [list(map(int, input().split()))[1:] for _ in range(N)]

lg = set(L[0])
update = True
used = [False] * N
used[0] = True
group = set(range(1, N))
while update:
    update = False
    for i in group:
        if used[i]:
            continue
        for l in lg:
            if l in L[i]:
                used[i] = True
                lg = lg.union(set(L[i]))
                update = True
# print(len(lg))
# print(lg)
if all(used):
    print("YES")
else:
    print("NO")

Submission Info

Judge Result