'commit'

TangDou/Topic/HDU1599.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define int long long
+#define endl "\n"
+const int INF = 0x3f3f3f3f;
+const int N = 110;
+
+int dis[N][N], g[N][N];
+int n, m, ans;
+
+void floyd() {
+    memcpy(dis, g, sizeof g);
+    for (int k = 1; k <= n; k++) {
+        // 最小环的DP操作
+        for (int i = 1; i < k; i++)         // 枚举i,j
+            for (int j = i + 1; j < k; j++) // 注意i,j,k不能相同
+                if (ans > dis[i][j] + g[i][k] + g[k][j])
+                    ans = dis[i][j] + g[i][k] + g[k][j];
+
+        for (int i = 1; i <= n; i++) // 原floyd
+            for (int j = 1; j <= n; j++)
+                if (dis[i][j] > dis[i][k] + dis[k][j])
+                    dis[i][j] = dis[i][k] + dis[k][j];
+    }
+}
+signed main() {
+    while (cin >> n >> m && (~n && ~m)) {
+        // 邻接矩阵初始化
+        for (int i = 1; i <= n; i++)
+            for (int j = 1; j <= n; j++)
+                if (i == j)
+                    g[i][j] = 0;
+                else
+                    g[i][j] = INF;
+
+        while (m--) {
+            int a, b, c;
+            cin >> a >> b >> c;
+            g[a][b] = g[b][a] = min(c, g[a][b]); // 防重边
+        }
+        ans = INF;
+        floyd();
+        if (ans == INF)
+            puts("It's impossible.");
+        else
+            cout << ans << endl;
+    }
+}