UVA 11637 Garbage Remembering Exam

#include <iostream>
#include <stdio.h>
#include <cstring>
#include <math.h>
#define MAX 100010

using namespace std;
int n,k;
long double fac[MAX];

void GetFacs()
{
    for(int i=;i<MAX;i++)
    {
        fac[i] = fac[i-] + log((long double)i);
    }
}

double ExpectedValue()
{
    int x;
    double p,e = n;
    if(n==) return ;
    for(int i=; i<=n; i++)
    {
        x = max(i-k-,) + max(n-i-k,);
        if(x-*k>=)
        {
            p = fac[x]+fac[n-*k-]-fac[n-]-fac[x-*k];
            e -= exp(p);
        }
    }
    return e;
}

int main()
{
    int t=;
    GetFacs();
    while(scanf("%d%d",&n,&k)!=EOF && !(n== && k==))
    {
        printf("Case %d: %.4lf\n", ++t, ExpectedValue());
    }
    return ;
}