'commit'

TangDou/Topic/HDU1704.cpp

@@ -0,0 +1,36 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define inf 0x3f3f3f3f
+const int N = 510;
+int n, m, x, y, ans;
+int g[N][N];
+
+void floyd() {
+    for (int k = 1; k <= n; k++)
+        for (int i = 1; i <= n; i++) {
+            if (!g[i][k]) continue; // floyd优化
+            for (int j = 1; j <= n; j++)
+                g[i][j] |= g[i][k] & g[k][j]; // 通过k传递,或运算
+        }
+}
+int main() {
+    int T;
+    cin >> T;
+    while (T--) {
+        cin >> n >> m;
+        memset(g, 0, sizeof g);
+        while (m--) {
+            cin >> x >> y;
+            g[x][y] = 1; // x<y
+        }
+        // 计算传递闭包
+        floyd();
+
+        ans = 0;
+        for (int i = 1; i <= n; i++) // 统计答案
+            for (int j = i + 1; j <= n; j++)
+                if (!g[i][j] && !g[j][i]) ans++; // 无法确定大小关系
+        cout << ans << endl;
+    }
+    return 0;
+}