'commit'

TangDou/AcWing/EulerPath/LianTongXing/floyd.cpp

@@ -0,0 +1,44 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int N = 1010; // 图的最大点数量
+int n, m;
+
+// 用floyd来判断起点是否可以达到终点
+int g[N][N]; // 邻接矩阵
+void floyd() {
+    for (int k = 1; k <= n; k++)
+        for (int i = 1; i <= n; i++)
+            for (int j = 1; j <= n; j++)
+                g[i][j] = g[i][j] || (g[i][k] && g[k][j]);
+}
+
+int main() {
+#ifndef ONLINE_JUDGE
+    freopen("in1.in", "r", stdin);
+    // freopen("in2.in", "r", stdin);
+#endif
+
+    // 采用邻接矩阵建图
+    cin >> n >> m;
+    // m条边
+    for (int i = 1; i <= m; i++) {
+        int a, b;
+        cin >> a >> b;
+        // 双向建边
+        g[a][b] = 1, g[b][a] = 1;
+    }
+    // 调用floyd
+    floyd();
+
+    for (int i = 1; i <= n; i++)
+        for (int j = 1; j <= n; j++)
+            if (!g[i][j]) {
+                printf("图不是连通的\n");
+                cout << i << " " << j << endl;
+                exit(0);
+            }
+    printf("图是连通的\n");
+    return 0;
+}