【BZOJ1076】[SCOI2008]奖励关【期望DP】【状压DP】

【题目链接】

写了忘发上来了。

/* Pigonometry */
#include <cstdio>
#include <algorithm>

using namespace std;

typedef double DB;

const int maxn = 20, maxk = 105, maxs = 1 << 16;

int n, k, s[maxn], w[maxn];
DB dp[maxk][maxs];

int main() {
scanf("%d%d", &k, &n);
for(int i = 1; i <= n; i++) {
scanf("%d", &w[i]);
while(1) {
int x; scanf("%d", &x);
if(!x) break;
s[i] |= 1 << (x - 1);
}
}

int S = 1 << n;
for(int i = k; i >= 1; i--) for(int j = 0; j < S; j++) {
for(int o = 1; o <= n; o++)
if((j & s[o]) == s[o]) dp[i][j] += max(dp[i + 1][j], dp[i + 1][j | (1 << (o - 1))] + w[o]);
else dp[i][j] += dp[i + 1][j];
dp[i][j] /= n;
}

printf("%.6lf\n", dp[1][0]);
return 0;
}