UVa11181 - Probability|Given(离散条件概率)

#include<cstdio>

double p[25],ans[25];
int n,r,vis[25];

void dfs(int k,int count)
{
    if(count==r){
        double tem=1;
        for(int i=1;i<=n;i++){
            if(vis[i]) tem *= p[i];
            else tem *= (1-p[i]);
        }
        ans[0]+=tem;
        for(int i=1;i<=n;i++)
            if(vis[i])
            ans[i]+=tem;
    }
    else{
        for(int i=k+1;i<=n;i++){
            vis[i]=1;
            dfs(i,count+1);
            vis[i]=0;
        }
    }
}

int main()
{
    int t=0;
    while(scanf("%d%d",&n,&r)){
        if(n==0&&r==0)
            break;
        t++;
        printf("Case %d:\n",t);
        for(int i=0;i<25;i++){
            ans[i]=0;
            vis[i]=0;
        }
        for(int i=1;i<=n;i++)
            scanf("%lf",&p[i]);
        dfs(0,0);
        for(int i=1;i<=n;i++)
            printf("%.6lf\n",ans[i]/ans[0]);
    }
    return 0;
}