题目:
#include<stdio.h>
int fuc(int x)
{
int m;
if(x==0||x==1) m=1;
else
{
m=x*fuc(x-1);
}
return m;
}
int main()
{
int n,k,m,h,i;
while(scanf("%d %d",&n,&k)!=EOF)
{
if(n==k||k==0) printf("%d\n",fuc(n)/fuc(n));
else
{
m=fuc(n-1);
h=fuc(k)*fuc(n-1-k);
i=fuc(k-1)*fuc(n-k);
printf("%d\n",m/h+m/i);
}
}
return 0;
}