結果

問題 No.1553 Lovely City
ユーザー H3PO4
提出日時 2022-11-26 15:42:44
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,105 ms / 2,000 ms
コード長 2,662 bytes
コンパイル時間 205 ms
コンパイル使用メモリ 82,304 KB
実行使用メモリ 190,384 KB
最終ジャッジ日時 2024-10-02 22:18:01
合計ジャッジ時間 25,409 ms
ジャッジサーバーID
(参考情報)
judge1 / judge5
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 26
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

from collections import defaultdict, deque
class UnionFind:
__slots__ = ["n", "parent", "height", "size"]
def __init__(self, n):
self.n = n
self.parent = [i for i in range(n)]
self.height = [1] * n
self.size = [1] * n
def find(self, x):
if self.parent[x] == x:
return x
else:
self.parent[x] = self.find(self.parent[x])
return self.parent[x]
def unite(self, x, y):
x = self.find(x)
y = self.find(y)
if x != y:
if self.height[x] < self.height[y]:
self.parent[x] = y
self.size[y] += self.size[x]
else:
self.parent[y] = x
self.size[x] += self.size[y]
if self.height[x] == self.height[y]:
self.height[x] += 1
def issame(self, x, y):
return self.find(x) == self.find(y)
def group_size(self, x):
return self.size[self.find(x)]
def group_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.parent) if i == x]
def group_count(self):
return len(self.roots())
def topological_sort(nodes, edges):
G = {n: [] for n in nodes}
deg = {n: 0 for n in nodes}
tps = []
for a, b in edges:
deg[b] += 1
G[a].append(b)
d = deque([i for i, x in deg.items() if not x])
while d:
v = d.popleft()
tps.append(v)
for x in G[v]:
deg[x] -= 1
if not deg[x]:
d.append(x)
if any(deg.values()):
return None # not DAG
return tps
N, M = map(int, input().split())
uf = UnionFind(N)
edges = tuple(tuple(int(x) - 1 for x in input().split()) for _ in range(M))
for u, v in edges:
uf.unite(u, v)
cc_edges = defaultdict(list)
cc_nodes = defaultdict(list)
for i in range(N):
cc_nodes[uf.find(i)].append(i)
for u, v in edges:
# assert uf.find(u) == uf.find(v)
cc_edges[uf.find(u)].append((u, v))
ans = []
for root in uf.roots():
nodes = cc_nodes[root]
if len(nodes) == 1:
continue
edges = cc_edges[root]
tps = topological_sort(nodes, edges)
if tps is None:
#
for i in range(len(nodes)):
j = i + 1
if j == len(nodes):
j = 0
ans.append((nodes[i], nodes[j]))
else:
# DAG
for i in range(len(tps) - 1):
ans.append((tps[i], tps[i + 1]))
print(len(ans))
for u, v in ans:
print(u + 1, v + 1)
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