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［AtCoder］ABC-272｜B - Everyone is Friends

に公開
Python
AtCoder
abc
tech

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提出結果

import itertools


def getIntMap():
    return map(int, input().split())


def getIntListRow(N):
    return [list(map(int, input().split())) for _ in range(N)]


def main():
    n, m = getIntMap()
    k = getIntListRow(m)

    a = sum([i + 1 for i in range(n - 1)])

    c = []
    for x in range(m):
        c += list(itertools.combinations(k[x][1:], 2))

    print('Yes' if a == len(set(c)) else 'No')


if __name__ == "__main__":
    main()

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