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()}

N, M, K = map(int, input().split())
uf = UnionFind(N)

friend =[[] for _ in range(N)]
block = [[] for _ in range(N)]
for _ in range(M):
    a, b = map(int, input().split())
    a, b = a-1, b-1
    uf.union(a, b)
    friend[a].append(b)
    friend[b].append(a)

for _ in range(K):
    c, d = map(int, input().split())
    c, d = c-1, d-1
    if uf.same(c, d):
        block[c].append(d)
        block[d].append(c)
ans = [0] * N
for i in range(N):
    ans[i] = uf.size(i) - len(friend[i]) - len(block[i]) - 1
print(*ans)

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()}

N, M, K = map(int, input().split())
uf = UnionFind(N)

friend =[[] for _ in range(N)]
block = [[] for _ in range(N)]
for _ in range(M):
    a, b = map(int, input().split())
    a, b = a-1, b-1
    uf.union(a, b)
    friend[a].append(b)
    friend[b].append(a)

for i in range(k):
    c, d = map(int, input().split())
    c, d = c-1, d-1
    if uf.same(c, d):
        block[c].append(d)
        block[d].append(c)
ans = [0] * N
for i in range(N):
    ans[i] = uf.size(i) - len(friend[i]) - len(block[i]) - 1
print(*ans)