Initial commit: C++ courseware

2.Course/2.深入浅出程序设计竞赛（提高篇）/最短路/C++源码/06b_transitive_closure.cpp

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+// B3611：至少经过一条边的可达性，不预先把对角线设为 true。
+#include <iostream>
+using namespace std;
+bool reach[105][105]{};
+
+void closure(int n) {
+    for (int k = 1; k <= n; ++k)
+        for (int i = 1; i <= n; ++i)
+            for (int j = 1; j <= n; ++j)
+                reach[i][j] = reach[i][j] || (reach[i][k] && reach[k][j]);
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+    int n, x;
+    cin >> n;
+    for (int i = 1; i <= n; ++i)
+        for (int j = 1; j <= n; ++j) {
+            cin >> x;
+            reach[i][j] = (x != 0);
+        }
+    closure(n);
+    for (int i = 1; i <= n; ++i)
+        for (int j = 1; j <= n; ++j)
+            cout << int(reach[i][j]) << (j == n ? '\n' : ' ');
+}