update

poj/3660.cow-contest/main.cc

@@ -0,0 +1,35 @@
+#include <cstdio>
+#include <cstring>
+
+using namespace std;
+
+const int N = 500;
+const int M = 4500;
+const int INF = 0x3F3F3F3F;
+
+bool win[N + 1][N + 1];
+
+int main() {
+  int n, m, a, b;
+  while (scanf("%d %d", &n, &m) != EOF) {
+    memset(win, 0, sizeof(win));
+    for (int i = 0; i < m; i++) {
+      scanf("%d %d", &a, &b);
+      win[a][b] = true;
+    }
+    for (int k = 1; k <= n; k++)
+      for (int i = 1; i <= n; i++)
+        for (int j = 1; j <= n; j++) win[i][j] |= win[i][k] & win[k][j];
+    int ans = 0;
+    for (int i = 1; i <= n; i++) {
+      int cnt = 0;
+      for (int j = 1; j <= n; j++) {
+        if (win[i][j]) cnt++;
+        if (win[j][i]) cnt++;
+      }
+      if (cnt == n - 1) ans++;
+    }
+    printf("%d\n", ans);
+  }
+  return 0;
+}