結果

問題 No.1813 Magical Stones
ユーザー MasKoaTSMasKoaTS
提出日時 2022-01-13 22:58:15
言語 Python3
(3.12.2 + numpy 1.26.4 + scipy 1.12.0)
結果
AC  
実行時間 1,051 ms / 2,000 ms
コード長 2,862 bytes
コンパイル時間 324 ms
コンパイル使用メモリ 13,184 KB
実行使用メモリ 70,044 KB
最終ジャッジ日時 2024-11-17 17:11:20
合計ジャッジ時間 19,338 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge3
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 30 ms
11,776 KB
testcase_01 AC 29 ms
11,648 KB
testcase_02 AC 29 ms
11,776 KB
testcase_03 AC 354 ms
63,436 KB
testcase_04 AC 30 ms
11,776 KB
testcase_05 AC 29 ms
11,776 KB
testcase_06 AC 47 ms
14,208 KB
testcase_07 AC 30 ms
12,032 KB
testcase_08 AC 33 ms
12,288 KB
testcase_09 AC 34 ms
12,672 KB
testcase_10 AC 32 ms
12,032 KB
testcase_11 AC 193 ms
29,208 KB
testcase_12 AC 30 ms
11,776 KB
testcase_13 AC 30 ms
11,648 KB
testcase_14 AC 350 ms
63,432 KB
testcase_15 AC 1,049 ms
69,920 KB
testcase_16 AC 1,039 ms
69,660 KB
testcase_17 AC 872 ms
61,920 KB
testcase_18 AC 1,048 ms
69,664 KB
testcase_19 AC 1,044 ms
70,044 KB
testcase_20 AC 1,051 ms
69,788 KB
testcase_21 AC 1,042 ms
69,656 KB
testcase_22 AC 1,028 ms
69,808 KB
testcase_23 AC 1,036 ms
69,536 KB
testcase_24 AC 37 ms
12,288 KB
testcase_25 AC 127 ms
22,768 KB
testcase_26 AC 59 ms
15,488 KB
testcase_27 AC 657 ms
55,124 KB
testcase_28 AC 736 ms
48,680 KB
testcase_29 AC 758 ms
57,016 KB
testcase_30 AC 680 ms
53,264 KB
testcase_31 AC 962 ms
67,264 KB
testcase_32 AC 31 ms
11,648 KB
testcase_33 AC 31 ms
11,648 KB
testcase_34 AC 57 ms
13,440 KB
testcase_35 AC 112 ms
15,872 KB
testcase_36 AC 46 ms
13,952 KB
testcase_37 AC 211 ms
21,180 KB
testcase_38 AC 253 ms
45,456 KB
testcase_39 AC 646 ms
57,092 KB
testcase_40 AC 49 ms
13,696 KB
testcase_41 AC 52 ms
12,800 KB
testcase_42 AC 115 ms
16,000 KB
testcase_43 AC 79 ms
15,488 KB
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 # 

import itertools as iter
import collections as coll
import heapq as hq
import bisect as bis
from decimal import Decimal as dec
from copy import deepcopy as dcopy
import math
import sys
sys.setrecursionlimit(10**6)
def input():
    return sys.stdin.readline().rstrip()
def getN():
	return int(sys.stdin.readline())
def getNs():
	return map(int,sys.stdin.readline().split())
def getList():
	return list(map(int,sys.stdin.readline().split()))
def strinps(n):
	return [sys.stdin.readline().rstrip() for _ in range(n)]
pi = 3.141592653589793
mod = 10**9+7
MOD = 998244353
INF = math.inf
dx = [1,0,-1,0];	dy = [0,1,0,-1]

"""
強連結成分分解（SCC）
from : https://github.com/ryusuke920/kyopro_educational_90_python/blob/main/solve_python/021.py
ref : https://manabitimes.jp/math/1250
"""

class SCC:
	def __init__(self, n):
		self.n = n
		self.graph = [[] for _ in range(n)]
		self.rev_graph = [[] for _ in range(n)]
		self.labels = [-1] * n
		self.lb_cnt = 0
	
	#グラフに有向辺を追加（逆向きのものを含む）
	def add_edge(self, v, nxt_v):
		self.graph[v].append(nxt_v)
		self.rev_graph[nxt_v].append(v)

	#SCCグラフの構成
	def build(self):
		self.post_order = []
		self.used = [False] * self.n
		for v in range(self.n):
			if(not self.used[v]):
				self._dfs(v)
		for v in reversed(self.post_order):
			if(self.labels[v] == -1):
				self._rev_dfs(v)
				self.lb_cnt += 1

	#SCCグラフを作る上でのDFS
	def _dfs(self, v):
		stack = [v, 0]
		while(stack):
			v, idx = stack[-2:]
			if not idx and self.used[v]:
				stack.pop()
				stack.pop()
			else:
				self.used[v] = True
				if idx < len(self.graph[v]):
					stack[-1] += 1
					stack.append(self.graph[v][idx])
					stack.append(0)
				else:
					stack.pop()
					self.post_order.append(stack.pop())

	#逆向きDFS
	def _rev_dfs(self, v):
		stack = [v]
		self.labels[v] = self.lb_cnt
		while stack:
			v = stack.pop()
			for nxt_v in self.rev_graph[v]:
				if self.labels[nxt_v] != -1:
					continue
				stack.append(nxt_v)
				self.labels[nxt_v] = self.lb_cnt

	#構成し終えたSCCグラフを連結成分ごとにリストにする
	def construct(self):
		self.dag = [[] for i in range(self.lb_cnt)]
		self.groups = [[] for i in range(self.lb_cnt)]
		for v, lb in enumerate(self.labels):
			for nxt_v in self.graph[v]:
				nxt_lb = self.labels[nxt_v]
				if lb == nxt_lb:
					continue
				self.dag[lb].append(nxt_lb)
			self.groups[lb].append(v)
		return self.dag, self.groups

"""
Main Code
"""

n,m = getNs()
route = [[] for _ in [0] * n]
scc = SCC(n)
for _ in [0] * m:
	a,b = [i - 1 for i in getNs()]
	route[a].append(b)
	scc.add_edge(a,b)
scc.build()
dag, _ = scc.construct()

s = len(dag)
if(s == 1):
	print(0)
	exit(0)

source = [True] * s
sink = [True] * s
for i in range(s):
	for j in dag[i]:
		sink[i] = source[j] = False
print(max(sum(source), sum(sink)))
0