OJ-Problems-Source/HDOJ/4089_autoAC.cpp

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#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#define eps 1e-10
#define N (1<<7)+5
#define inf 1<<20
#define zero(a) (fabs(a)<eps)
#define lson (step<<1)
#define rson (step<<1|1)
using namespace std;
double p1,p2,p3,p4,p21,p31,p41;
double dp[2005][2005],c[2005];
int n,m,k;
int main(){
while(scanf("%d%d%d%lf%lf%lf%lf",&n,&m,&k,&p1,&p2,&p3,&p4)!=EOF){
if(zero(p4)) {puts("0.00000");continue;}
p21=p2/(1-p1);
p31=p3/(1-p1);
p41=p4/(1-p1);
dp[1][1]=p4/(1-p1-p2);
for(int i=2;i<=n;i++){
for(int j=2;j<=(i<k?i:k);j++)
c[j]=dp[i-1][j-1]*p31+p41;
for(int j=k+1;j<=i;j++)
c[j]=dp[i-1][j-1]*p31;
double p=1,tmp=0;
for(int j=i;j>1;j--){
tmp+=p*c[j];
p*=p21;
}
dp[i][i]=(tmp+p*p41)/(1-p*p21);
dp[i][1]=p21*dp[i][i]+p41;
for(int j=2;j<i;j++)
dp[i][j]=p21*dp[i][j-1]+c[j];
}
printf("%.5f\n",dp[n][m]);
}
return 0;
}