Submission #5549446

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Source Code Expand

class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
ass = set()
N,K=map(int,input().split())
uni = UnionFind(K-1)
for _ in range(N):
    t = list(map(int,input().split()))
    ass.add(t[1]-1)
    if t[0] !=1:
        for k in t[2:]:
            uni.union(t[1]-1,k-1)
            ass.add(k-1)
            #print(t[1]-1,k-1)
p = set()
for i in ass:
    d = uni.find(i)
    p.add(d)
print("YES" if 1 ==len(p) else "NO")

Submission Info

Judge Result