Submission #11231940

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Source Code Expand

class UnionFind:
    def __init__(self, n):
        self.n = n
        self.p = [e for e in range(n)]
        self.rank = [0] * n
        self.size = [1] * n

    def same(self, u, v):
        return self.find_set(u) == self.find_set(v)

    def unite(self, u, v):
        u = self.find_set(u)
        v = self.find_set(v)

        if u == v:
            return

        if self.rank[u] > self.rank[v]:
            self.p[v] = u
            self.size[u] += self.size[v]
        else:
            self.p[u] = v
            self.size[v] += self.size[u]
            if self.rank[u] == self.rank[v]:
                self.rank[v] += 1

    def find_set(self, u):
        if u != self.p[u]:
            self.p[u] = self.find_set(self.p[u])

        return self.p[u]

    def update_p(self):
        for u in range(self.n):
            self.find_set(u)

    def get_size(self, u):
        return self.size[self.find_set(u)]


n, m = map(int, input().split())
l = []
for _ in range(n):
    k, *ls = map(int, input().split())
    l.append(ls)

uf = UnionFind(m)

cnt = [0] * m
for li in l:
    for e1, e2 in zip(li, li[1:]):
        e1 -= 1
        e2 -= 1
        cnt[e1] = 1
        cnt[e2] = 1
        uf.unite(e1, e2)

if max(uf.size) == sum(cnt):
    ans = "YES"
else:
    ans = "NO"

print(ans)

Submission Info

Judge Result