From dd85b22ffb38793925e6750aa3860066f04474b2 Mon Sep 17 00:00:00 2001
From: oncsr <khj20006@naver.com>
Date: Tue, 18 Feb 2025 13:06:02 +0900
Subject: [PATCH] =?UTF-8?q?[20250218]=20BOJ=20/=20G4=20/=20=ED=82=A4=20?=
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 create mode 100644 "khj20006/202502/18 BOJ G4 \355\202\244 \354\210\234\354\204\234.md"

diff --git "a/khj20006/202502/18 BOJ G4 \355\202\244 \354\210\234\354\204\234.md" "b/khj20006/202502/18 BOJ G4 \355\202\244 \354\210\234\354\204\234.md"
new file mode 100644
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--- /dev/null
+++ "b/khj20006/202502/18 BOJ G4 \355\202\244 \354\210\234\354\204\234.md"	
@@ -0,0 +1,80 @@
+### 플로이드
+
+```cpp
+
+#include <iostream>
+#include <vector>
+using namespace std;
+int main()
+{
+	int N, M;
+	cin >> N >> M;
+	vector<vector<bool>> D(N + 1, vector<bool>(N + 1));
+	for (int i = 1; i <= N; i++) D[i][i] = 1;
+	for (int i = 0, a, b; i < M; i++) {
+		cin >> a >> b;
+		D[a][b] = 1;
+	}
+
+	for (int i = 1; i <= N; i++) for (int j = 1; j <= N; j++) for (int k = 1; k <= N; k++) {
+		if (D[j][i] && D[i][k]) D[j][k] = 1;
+	}
+
+	int ans = 0;
+	for (int i = 1; i <= N; i++) {
+		int res = 0;
+		for (int j = 1; j <= N; j++) res += D[i][j] + D[j][i];
+		ans += res == N + 1;
+	}
+	cout << ans;
+
+}
+
+```
+
+### 위상 정렬
+
+```cpp
+
+#include <iostream>
+#include <vector>
+#include <queue>
+using namespace std;
+
+int main()
+{
+	int N, M;
+	cin >> N >> M;
+	vector<vector<int>> V(N + 1);
+	vector<vector<bool>> D(N + 1, vector<bool>(N + 1));
+	vector<int> in(N + 1);
+	for (int i = 1; i <= N; i++) D[i][i] = 1;
+	for (int i = 0, a, b; i < M; i++) {
+		cin >> a >> b;
+		V[a].push_back(b);
+		in[b]++;
+	}
+
+	queue<int> Q;
+	for (int i = 1; i <= N; i++) if (!in[i]) Q.push(i);
+
+	while (!Q.empty()) {
+		int x = Q.front();
+		Q.pop();
+		for (int i : V[x]) {
+			for (int j = 1; j <= N; j++) if (D[j][x]) D[j][i] = 1;
+			if (!(--in[i])) Q.push(i);
+		}
+	}
+
+	int ans = 0;
+	for (int i = 1; i <= N; i++) {
+		int res = 0;
+		for (int j = 1; j <= N; j++) res += D[i][j] + D[j][i];
+		ans += res == N + 1;
+	}
+	cout << ans;
+
+}
+
+```