HDU4815/计数DP

#include<bits/stdc++.h>
const int maxn = 40*1050;
double dp[maxn];
int a[55];
int T,n;
double p;
int main ()
{
    scanf("%d",&T);
    while(T--)
    {
        int sum=0;
        scanf("%d%lf",&n,&p);
        for(int i = 1;i <= n;i++)
        {
            scanf("%d",&a[i]);
            sum += a[i];
        }
        for(int i = 0;i <= sum;i++)
            dp[i]=0;
        dp[0]=1;
        for(int i = 1;i <= n;i++)
            for(int j = sum;j >= a[i];j--)
                dp[j] += dp[j-a[i]];
        double nu = pow(2,n);
        for(int i = 0;i <= sum;i++)
            dp[i] /= nu;
        double fal = 0.0;
        for(int k = 0;k <= sum;k++)
        {
            fal += dp[k];
            if(fal >= p)
            {
                printf("%d\n",k);
                break;
            }
        }
    }
    return 0;
}