#578. 【SCOI2008】奖励关

https://sjzezoj.com/submission/64245

S2OJ/578/578.cpp

@@ -0,0 +1,45 @@
+#include <iostream>
+#include <iomanip>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 15 + 2,
+          K = 105;
+
+int k, n, p[N], s[N];
+double f[K][1 << N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> k >> n;
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> p[i];
+
+        while (cin >> x, x) {
+            s[i] |= 1 << x - 1;
+        }
+    }
+
+    for (int i = k; i; i--) {
+        for (int t = 0; t < 1 << n; t++) {
+            for (int j = 1; j <= n; j++) {
+                if ((t & s[j]) == s[j]) {
+                    f[i][t] += std::max(f[i + 1][t], f[i + 1][t | (1 << j - 1)] + p[j]);
+                } else {
+                    f[i][t] += f[i + 1][t];
+                }
+            }
+
+            f[i][t] /= n;
+        }
+    }
+
+    cout << std::fixed << std::setprecision(6) << f[1][0] << endl;
+
+    return 0;
+}