Submission #6365183

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Source Code Expand

N,M = map(int,input().split())
KL = [list(map(int,input().split())) for _ in [0]*N ]

E = [[[] for _ in [0]*N] , [[] for _ in [0]*M]]
for i,kl in enumerate(KL):
    for l in kl[1:]:
        E[0][i].append(l-1)
        E[1][l-1].append(i)

Check = [[False]*N,[False]*M]
Check[0][0] = True
q = [[0,0]]
while q:
    cl,i = q.pop()
    for j in E[cl][i]:
        if Check[1-cl][j]:continue
        q.append([1-cl,j])
        Check[1-cl][j] = True

if sum(Check[0]) == N:
    print("YES")
else:
    print("NO")

Submission Info

Judge Result