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/06a_floyd_general.cpp

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+// 教学模板：有向图，无负环。输入 n m，随后 m 行 u v w。
+// 输出 n 行最短距离矩阵，不可达写 INF。这个输出约定为教学自拟。
+// 建议教学数据 n<=500、|w|<=10^9，有限路长和候选之和远小于 INF。
+#include <algorithm>
+#include <iostream>
+#include <vector>
+using namespace std;
+using ll = long long;
+const ll INF = 1LL << 60;
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+    int n, m;
+    cin >> n >> m;
+    vector<vector<ll>> d(n + 1, vector<ll>(n + 1, INF));
+    for (int i = 1; i <= n; ++i) d[i][i] = 0;
+    for (int t = 0; t < m; ++t) {
+        int u, v;
+        ll w;
+        cin >> u >> v >> w;
+        d[u][v] = min(d[u][v], w);
+    }
+    for (int k = 1; k <= n; ++k)
+        for (int i = 1; i <= n; ++i)
+            for (int j = 1; j <= n; ++j) {
+                if (d[i][k] == INF || d[k][j] == INF) continue;
+                ll nd = d[i][k] + d[k][j];
+                d[i][j] = min(d[i][j], nd);
+            }
+    for (int i = 1; i <= n; ++i) {
+        for (int j = 1; j <= n; ++j) {
+            if (j > 1) cout << ' ';
+            if (d[i][j] == INF) cout << "INF";
+            else cout << d[i][j];
+        }
+        cout << '\n';
+    }
+}