Submission #5542295

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Source Code Expand

N, M = map(int, input().split())
X = [i for i in range(M)]
Y = [0] * M
def par(i):
    if X[i] == i:
        return i
    t = par(X[i])
    X[i] = t
    return t
c = 0
for _ in range(N):
    Z = [int(a) - 1 for a in input().split()][1:]
    i = Z[0]
    for j in Z:
        if Y[j] == 0:
            c += 1
            Y[j] = 1
        pi = par(i)
        pj = par(j)
        if pi != pj:
            X[pj] = pi
            c -= 1
if c == 1:
    print("YES")
else:
    print("NO")

Submission Info

Judge Result