P2850 [USACO06DEC]Wormholes G

R57649137

Luogu/problem/P2850/P2850.cpp

@@ -0,0 +1,37 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int t, n, m, w, u, v, p, g[505][505];
+
+bool check() {
+    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]);
+            }
+            if (g[i][i] < 0) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+int main() {
+    cin >> t;
+    while (t--) {
+        memset(g, 0x3f, sizeof(g));
+        cin >> n >> m >> w;
+        for (int i = 1; i <= m; i++) {
+            cin >> u >> v >> p;
+            g[u][v] = g[v][u] = min(g[u][v], p);
+        }
+        for (int i = 1; i <= w; i++) {
+            cin >> u >> v >> p;
+            g[u][v] = min(g[u][v], -p);
+        }
+        cout << (check() ? "YES" : "NO") << endl;
+    }
+    return 0;
+}