zoj 1938 Binomial Showdown

#include <cstdio>#include <cstring>#include <math.h>typedef long long LL;LL  ans,n,k;int main(){    while(scanf("%lld%lld",&n,&k),n)    {        ans=1;        if(k == 0)        { printf("1n"); continue;        }        k=n-k>k?k:n-k;        for(int i=1; i<=k; i++)        { ans=ans*(n-i+1)/i;        }        printf("%lldn",ans);    }    return 0;}