P6175 无向图的最小环问题

R53047373

Luogu/problem/P6175/P6175.cpp

@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+long long n, m, u, v, d, f1[105][105], f2[105][105], ans = 0x3f3f3f3f;
+
+int main() {
+    cin >> n >> m;
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= n; j++) {
+            f1[i][j] = f2[i][j] = i == j ? 0 : 0x3f3f3f3f;
+        }
+    }
+    for (int i = 1; i <= m; i++) {
+        cin >> u >> v >> d;
+        f1[u][v] = min(f1[u][v], d);
+        f1[v][u] = min(f1[v][u], d);
+        f2[u][v] = min(f2[u][v], d);
+        f2[v][u] = min(f2[v][u], d);
+    }
+    for (int k = 1; k <= n; k++) {
+        for (int i = 1; i < k; i++) {
+            for (int j = i + 1; j < k; j++) {
+                ans = min(ans, f1[i][j] + f2[i][k] + f2[k][j]);
+            }
+        }
+        for (int i = 1; i <= n; i++) {
+            for (int j = 1; j <= n; j++) {
+                f1[i][j] = min(f1[i][j], f1[i][k] + f1[k][j]);
+                f1[j][i] = f1[i][j];
+            }
+        }
+    }
+    if (ans == 0x3f3f3f3f) {
+        cout << "No solution." << endl;
+    } else {
+        cout << ans << endl;
+    }
+    return 0;
+}