P1613 跑路

R54032506

Luogu/problem/P1613/P1613.cpp

@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, u, v, g[55][55];
+bool f[55][55][55];
+
+int main() {
+    cin >> n >> m;
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= n; j++) {
+            g[i][j] = i == j ? 0 : 0x3f3f3f3f;
+        }
+    }
+    for (int i = 1; i <= m; i++) {
+        cin >> u >> v;
+        g[u][v] = f[u][v][0] = 1;
+    }
+    for (int p = 1; p <= 32; p++) {
+        for (int k = 1; k <= n; k++) {
+            for (int i = 1; i <= n; i++) {
+                for (int j = 1; j <= n; j++) {
+                    if (f[i][k][p - 1] && f[k][j][p - 1]) {
+                        f[i][j][p] = true;
+                        g[i][j] = 1;
+                    }
+                }
+            }
+        }
+    }
+    for (int k = 1; k <= n; k++) {
+        for (int i = 1; i <= n; i++) {
+            for (int j = 1; j <= n; j++) {
+                g[i][j] = min(g[i][j], g[i][k] + g[k][j]);
+            }
+        }
+    }
+    cout << g[1][n] << endl;
+    return 0;
+}