結果

問題 No.1813 Magical Stones
ユーザー MasKoaTSMasKoaTS
提出日時 2021-09-23 11:52:42
言語 Python3
(3.12.2 + numpy 1.26.4 + scipy 1.12.0)
結果
AC  
実行時間 1,540 ms / 2,000 ms
コード長 1,986 bytes
コンパイル時間 158 ms
コンパイル使用メモリ 11,192 KB
実行使用メモリ 57,216 KB
最終ジャッジ日時 2023-09-23 07:03:47
合計ジャッジ時間 25,621 ms
ジャッジサーバーID
（参考情報） 		judge11 / judge14
このコードへのチャレンジ
（要ログイン）

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 17 ms
8,524 KB
testcase_01 AC 17 ms
8,432 KB
testcase_02 AC 17 ms
8,568 KB
testcase_03 AC 391 ms
53,180 KB
testcase_04 AC 18 ms
8,120 KB
testcase_05 AC 18 ms
8,596 KB
testcase_06 AC 39 ms
10,408 KB
testcase_07 AC 17 ms
8,580 KB
testcase_08 AC 21 ms
8,944 KB
testcase_09 AC 23 ms
9,128 KB
testcase_10 AC 21 ms
8,928 KB
testcase_11 AC 268 ms
23,604 KB
testcase_12 AC 18 ms
8,484 KB
testcase_13 AC 18 ms
8,080 KB
testcase_14 AC 387 ms
53,116 KB
testcase_15 AC 1,515 ms
56,964 KB
testcase_16 AC 1,515 ms
57,152 KB
testcase_17 AC 1,429 ms
47,752 KB
testcase_18 AC 1,500 ms
57,216 KB
testcase_19 AC 1,505 ms
56,908 KB
testcase_20 AC 1,515 ms
56,832 KB
testcase_21 AC 1,520 ms
56,976 KB
testcase_22 AC 1,540 ms
56,784 KB
testcase_23 AC 1,528 ms
56,944 KB
testcase_24 AC 28 ms
9,108 KB
testcase_25 AC 159 ms
18,096 KB
testcase_26 AC 58 ms
11,684 KB
testcase_27 AC 1,036 ms
44,984 KB
testcase_28 AC 1,253 ms
38,736 KB
testcase_29 AC 1,208 ms
46,368 KB
testcase_30 AC 1,117 ms
43,520 KB
testcase_31 AC 1,363 ms
55,120 KB
testcase_32 AC 18 ms
8,416 KB
testcase_33 AC 17 ms
8,424 KB
testcase_34 AC 57 ms
9,904 KB
testcase_35 AC 176 ms
11,744 KB
testcase_36 AC 38 ms
10,320 KB
testcase_37 AC 370 ms
16,456 KB
testcase_38 AC 296 ms
37,712 KB
testcase_39 AC 953 ms
46,760 KB
testcase_40 AC 43 ms
10,124 KB
testcase_41 AC 58 ms
9,368 KB
testcase_42 AC 183 ms
11,960 KB
testcase_43 AC 101 ms
11,728 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 # 

"""
Strongly Connected Component
source ; https://github.com/ryusuke920/kyopro_educational_90_python/blob/main/solve_python/021.py
"""

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
	
	def add_edge(self, v, nxt_v):
		self.graph[v].append(nxt_v)
		self.rev_graph[nxt_v].append(v)

	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

	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())

	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

	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 = map(int,input().split())

scc = SCC(n)
for _ in range(m):
    a,b = map(int,input().split())
    scc.add_edge(a-1,b-1)
scc.build()

DAG,_ = scc.construct()
t = len(DAG)

if(t <= 1):
	print(0)
	exit(0)

source = [True]*t
sink = [True]*t
for i in range(t):
	for j in set(DAG[i]):
		source[i] = sink[j] = False
ans = max(sum(source),sum(sink))

print(ans)
0