【cojs1487】麻球繁衍

概率与期望

#include<iostream>#include<cstring>#include<cstdio>#include<cmath>using namespace std;inline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;}int N,n,k,m;double p[1001],ans[1001];int main(){freopen("tribbles.in","r",stdin);freopen("tribbles.out","w",stdout);N=read();for(int t=1;t<=N;t++){n=read();k=read();m=read();for(int i=0;i<n;i++)scanf("%lf",&p[i]);memset(ans,0,sizeof(ans));ans[m]=p[0];for(int i=m-1;i>=1;i--){ans[i]=p[0];for(int j=1;j<n;j++)ans[i]+=p[j]*pow(ans[i+1],j);}double P=1;for(int i=1;i<=k;i++)P*=ans[1];printf("Case #%d: %.7lf\n",t,P);}return 0;}