結果

問題 No.1553 Lovely City
ユーザー mkawa2
提出日時 2023-01-12 00:32:53
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 803 ms / 2,000 ms
コード長 2,341 bytes
コンパイル時間 258 ms
コンパイル使用メモリ 81,896 KB
実行使用メモリ 154,016 KB
最終ジャッジ日時 2024-12-22 18:06:43
合計ジャッジ時間 18,277 ms
ジャッジサーバーID
(参考情報)
judge3 / judge1
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

import sys
# sys.setrecursionlimit(1000005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
md = 10**9+7
# md = 998244353
class UnionFind:
def __init__(self, n):
self.table = [-1]*n
self.mem = [[u] for u in range(n)]
self.cnt = n
def root(self, u):
stack = []
while self.table[u] >= 0:
stack.append(u)
u = self.table[u]
for v in stack: self.table[v] = u
return u
def same(self, u, v):
return self.root(u) == self.root(v)
def merge(self, u, v):
u = self.root(u)
v = self.root(v)
if u == v: return False
su = -self.table[u]
sv = -self.table[v]
if su < sv: u, v = v, u
self.table[u] = -su-sv
self.table[v] = u
self.mem[u] += self.mem[v]
self.mem[v].clear()
self.cnt -= 1
return True
def member(self, u):
return self.mem[self.root(u)]
#
def size(self, u):
return -self.table[self.root(u)]
n, m = LI()
to = [[] for _ in range(n)]
deg = [0]*n
uf = UnionFind(n)
for _ in range(m):
u, v = LI1()
to[u].append(v)
deg[v] += 1
uf.merge(u, v)
ans = []
for uu in uf.mem:
if len(uu) == 1: continue
topo = []
st = []
for u in uu:
if deg[u] == 0: st.append(u)
while st:
u = st.pop()
topo.append(u)
for v in to[u]:
deg[v] -= 1
if deg[v] == 0: st.append(v)
if len(topo) == len(uu):
for i in range(len(topo)-1):
ans.append((topo[i], topo[i+1]))
else:
for i in range(len(uu)):
ans.append((uu[i-1], uu[i]))
print(len(ans))
for u, v in ans: print(u+1, v+1)
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