108。冗余连接

class UnionFind():
    def __init__(self,size):
        self.parent = list(range(size+1))
    def find(self,u):
        if self.parent[u] != u:
            self.parent[u] = self.find(self.parent[u])
        return self.parent[u]
    def union(self,u,v):
        findu = self.find(u)
        findv = self.find(v)
        if findu != findv:
            self.parent[findv] = findu
    def is_same(self,u,v):
        return self.find(u) == self.find(v)

def main():
    n = int(input())
    num = []
    for i in range(n):
        num.append(list(map(int,input().split())))
    res = []
    a = UnionFind(n)
    for i in range(n):
        u = num[i][0]
        v = num[i][1]
        if a.find(v) != a.find(u):
            a.union(u,v)
        else:
            res.append([u,v])
    print(' '.join(map(str,res[-1])))
if __name__ == "__main__":
    main()

108. 冗余连接