花园 期望DP

SCOI day2 T1；

分析：实在不知道哪里可以说的，期望dp的基本模板吧。

# include <iostream>
# include <cstdio>
# include <cstdlib>
# include <cstring>
# include <cmath>
# include <vector>
# include <algorithm>
using namespace std;
inline int read()
{
    register int i=0;
    char ch=getchar();
    while(ch<'0'||ch>'9')
    {
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
    {
        i=(i<<3)+(i<<1)+ch-'0';
        ch=getchar();
    }
    return i;
}
double a[1005][1005],p[1005][1005],pt[1005][1005];
int n,m,k;
int main()
{

    n=read(),m=read(),k=read();
    for(register int i=1;i<=n;++i)
        for(register int j=1;j<=m;++j) a[i][j]=read();
    for(register int i=1;i<=n;++i)
        for(register int j=1;j<=m;++j) scanf("%lf",&p[i][j]);
        double ans=0;
    ans=a[1][1];pt[1][1]=1;
    for(register int i=1;i<=n;++i)
        for(register int j=1;j<=m;++j)
        {
            if(i==1&&j==1) continue;
            pt[i][j]=p[i][j-1]*pt[i][j-1]+pt[i-1][j]*(1-p[i-1][j]);
            ans+=pt[i][j]*a[i][j];a[i][j]=pt[i][j]*a[i][j];
        }
        if(k==0)
        {
            cout<<(int)(ans+0.5)<<endl;
            return 0;
    }
    for(register int i=1;i<=n;++i)
        for(register int j=1;j<=m;++j) a[i][j]+=max(a[i-1][j],a[i][j-1]);
    cout<<(int)(ans-a[n][m]+0.5)<<endl;
    return 0;

}