Problem: An SNS has N users - User 1, User 2, \cdots, User N.  Between these N users, there are some relationships - M _friendships_ and K _blockships_.  For each i = 1, 2, \cdots, M, there is a bidirectional friendship between User A_i and User B_i.  For each i = 1, 2, \cdots, K, there is a bidirectional blockship between User C_i and User D_i.  We define User a to be a _friend candidate_ for User b when all of the following four conditions are satisfied:    * a \neq b.   * There is not a friendship between User a and User b.   * There is not a blockship between User a and User b.   * There exists a sequence c_0, c_1, c_2, \cdots, c_L consisting of integers between 1 and N (inclusive) such that c_0 = a, c_L = b, and there is a friendship between User c_i and c_{i+1} for each i = 0, 1, \cdots, L - 1.  For each user i = 1, 2, ... N, how many friend candidates does it have?

Submission attempts (in order):
import sys
from collections import defaultdict
def input(): return sys.stdin.readline().rstrip()

class UnionFind:
    def __init__(self, n):
        self.n = n + 1
        self.parents = [-1] * (n + 1)
        self.mem = [[] for _ in range(n+1)]

    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 same(self, x, y):
        return self.find(x) == self.find(y)
    
    def size(self, x):
        return -self.parents[self.find(x)]
    
    def members(self, x):
        root = self.find(x)
        if not self.mem[root]:
            self.mem[root] = [i for i in range(1, self.n) if self.find(i) == root]
        return self.mem[root]

def main():
    N, M, K = map(int, input().split())
    friend_or_block = [set() for _ in range(N+1)]
    friendsGroup = UnionFind(N)
    for _ in range(M):
        a, b = map(int, input().split())
        friendsGroup.union(a, b)
        friend_or_block[a].add(b)
        friend_or_block[b].add(a)

    for _ in range(K):
        c, d = map(int, input().split())
        friend_or_block[c].add(d)
        friend_or_block[d].add(c)

    memo = defaultdict(int)
    ans = [0] * (N + 1)
    for i in range(1, N+1):
        root = friendsGroup.find(i)
        if memo[root] == 0:
            memo[root] = len([v for v in friendsGroup.members(i) if v not in friend_or_block[i]]) - 1
        ans[i] = memo[root]
    print(*ans[1:])

if __name__ == '__main__':
    main()


import sys
from collections import defaultdict
def input(): return sys.stdin.readline().rstrip()

class UnionFind:
    def __init__(self, n):
        self.parents = [-1] * (n + 1)

    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 same(self, x, y):
        return self.find(x) == self.find(y)
    
    def size(self, x):
        return -self.parents[self.find(x)]

def main():
    N, M, K = map(int, input().split())

    friends = defaultdict(lambda : 1)
    friendsGroup = UnionFind(N)
    for _ in range(M):
        a, b = map(int, input().split())
        friendsGroup.union(a, b)
        friends[a] += 1
        friends[b] += 1

    blocks = defaultdict(int)
    for _ in range(K):
        c, d = map(int, input().split())
        if friendsGroup.same(c, d):
            blocks[c] += 1
            blocks[d] += 1

    ans = [friendsGroup.size(i) - friends[i] - blocks[i] for i in range(1, N+1)]
    print(*ans)

if __name__ == '__main__':
    main()


Verdicts: Wrong Answer

Accepted