Submission #11236305

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Source Code Expand

class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n
    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        if self.parents[x] > self.parents[y]:
            x, y = y, x
        self.parents[x] += self.parents[y]
        self.parents[y] = x
    def size(self, x):
        return -self.parents[self.find(x)]
    def same(self, x, y):
        return self.find(x) == self.find(y)
    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]
    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]
    def group_count(self):
        return len(self.roots())
import sys
input=sys.stdin.readline
n,m = map(int, input().split())
uf = UnionFind(m)
lang=set()
for i in range(n):
    lis = list(map(int,input().split()))
    for i in range(1,len(lis)-1):
        lang.add(lis[i]-1)
        uf.union(lis[i]-1,lis[i+1]-1)
    lang.add(lis[-1]-1)
e = next(iter(lang))
if lang == set(uf.members(e)):
    print("YES")
else:
    print("NO")

Submission Info

Judge Result