Problem p02762 (python)

Fixed submission:
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())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

    def __str__(self):
        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())


if __name__ == "__main__":
    n, m, k = map(int, input().split())
    uf = UnionFind(n)

    friendlist = dict()
    for i in range(m):
        tmp = list(map(int, input().split()))
        uf.union(tmp[0]-1, tmp[1]-1)
        if tmp[0] - 1 not in friendlist:
            friendlist[tmp[0]-1] = [tmp[1]-1]
        else:
            friendlist[tmp[0]-1].append(tmp[1]-1)
        if tmp[1] - 1 not in friendlist:
            friendlist[tmp[1]-1] = [tmp[0]-1]
        else:
            friendlist[tmp[1]-1].append(tmp[0]-1)

    blocklist = dict()
    for i in range(k):
        tmp = list(map(int, input().split()))
        if tmp[0] - 1 not in blocklist:
            blocklist[tmp[0]-1] = [tmp[1]-1]
        else:
            blocklist[tmp[0]-1].append(tmp[1]-1)
        if tmp[1] - 1 not in blocklist:
            blocklist[tmp[1]-1] = [tmp[0]-1]
        else:
            blocklist[tmp[1]-1].append(tmp[0]-1)

    ans = list()
    for i in range(n):
        blocknum = 0
        if i in blocklist:
            for ii in blocklist[i]:
                if uf.find(ii) == uf.find(i):
                    blocknum += 1
        friendnum = 0
        if i in friendlist:
            friendnum = len(friendlist[i])

        print(str(uf.size(i) - friendnum - blocknum - 1))

Buggy submission (verdict: Runtime Error):
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())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

    def __str__(self):
        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())


if __name__ == "__main__":
    n, m, k = map(int, input().split())
    uf = UnionFind(n)

    friendlist = dict()
    for i in range(m):
        tmp = list(map(int, input().split()))
        uf.union(tmp[0]-1, tmp[1]-1)
        if tmp[0] - 1 not in friendlist:
            friendlist[tmp[0]-1] = [tmp[1]-1]
        else:
            friendlist[tmp[0]-1].append(tmp[1]-1)
        if tmp[1] - 1 not in friendlist:
            friendlist[tmp[1]-1] = [tmp[0]-1]
        else:
            friendlist[tmp[1]-1].append(tmp[0]-1)

    blocklist = dict()
    for i in range(k):
        tmp = list(map(int, input().split()))
        if tmp[0] - 1 not in blocklist:
            blocklist[tmp[0]-1] = [tmp[1]-1]
        else:
            blocklist[tmp[0]-1].append(tmp[1]-1)
        if tmp[1] - 1 not in blocklist:
            blocklist[tmp[1]-1] = [tmp[0]-1]
        else:
            blocklist[tmp[1]-1].append(tmp[0]-1)

    for i in range(n):
        blocknum = 0
        if i in blocklist:
            for ii in blocklist[i]:
                if uf.find(ii) == uf.find(i):
                    blocknum += 1
        if i in friendlist:
            friendnum = len(friendlist[i])

        print(str(uf.size(i) - friendnum - blocknum - 1))