poj 2151 Check the difficulty of problems 夜

http://poj.org/problem?id=2151

dp不是问题 问题在于这是道数学题 亲人呀 最恨数学题

尤其是和概率有关 代码很乱呀 有木有

#include<iostream>
#include<string>
#include<string.h>
#include<queue>
#include<math.h>
#include<stdio.h>
#include<map>

using namespace std;
double probability[1005][35];
double a[35][35];
double dp(int i,int j,int l)
{
    if(a[i][j]>=0.0)
    {
        return a[i][j];
    }
    if(j==0)
    {
        if(i==1)
        a[i][j]=(1-probability[l][i]);
        else
        a[i][j]=(1-probability[l][i])*dp(i-1,0,l);
        return a[i][j];
    }
    if(j==1&&i==1)
    {
       a[i][j]=probability[l][i];
       return a[i][j];
    }
    if(i<j)
    {
        a[i][j]=0.0;
        return a[i][j];
    }
    if(i==j)
    {
        a[i][j]=probability[l][i]*dp(i-1,j-1,l);
        return a[i][j];
    }
    if(i>j)
    {
        a[i][j]=probability[l][i]*dp(i-1,j-1,l);
        a[i][j]=a[i][j]+dp(i-1,j,l)*(1-probability[l][i]);
        return a[i][j];
    }

}
int main()
{

    int m,t,n;
    while(scanf("%d %d %d",&m,&t,&n)!=EOF)
    {
        if(m==0&&t==0&&n==0)
        break;
        double w,anstemp=1.0;
        for(int i=1;i<=t;++i)
        {
            w=1.0;
            for(int j=1;j<=m;++j)
            {
                scanf("%lf",&probability[i][j]);
                w=w*(1.0-probability[i][j]);
            }
            anstemp=anstemp*(1.0-w);
        }
        double ans=1.0;
        for(int l=1;l<=t;++l)
        {
            for(int i=0;i<=m;++i)
            {
                for(int j=0;j<=m;++j)
                {
                    a[i][j]=-1.0;
                }
            }
            w=0.0;
            int i;
            for(i=1;i<n;++i)
            {
                w=w+dp(m,i,l);
            }

            ans=ans*(w);
        }
        printf("%.3f\n",anstemp-ans);

    }
    return 0;
}