853. 有边数限制的最短路

https://www.acwing.com/problem/content/submission/code_detail/6594231/

AcWing/853/853.cpp

@@ -0,0 +1,34 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+struct node {
+    int u, v, w;
+} g[10005];
+
+int n, m, k, dist[505], backup[505];
+
+void bellman_ford() {
+    memset(dist, 0x3f, sizeof(dist));
+    dist[1] = 0;
+    for (int i = 1; i <= k; i++) {
+        memcpy(backup, dist, sizeof(dist));
+        for (int j = 1; j <= m; j++) {
+            dist[g[j].v] = min(dist[g[j].v], backup[g[j].u] + g[j].w);
+        }
+    }
+}
+
+int main() {
+    cin >> n >> m >> k;
+    for (int i = 1; i <= m; i++) {
+        cin >> g[i].u >> g[i].v >> g[i].w;
+    }
+    bellman_ford();
+    if (dist[n] > 0x1f1f1f1f) {
+        cout << "impossible" << endl;
+    } else {
+        cout << dist[n] << endl;
+    }
+    return 0;
+}