HOJ ( acm.hdu.edu.cn ) 1570

#include<iostream>
using namespace std;
unsigned long long C(int n,int m)
{
   unsigned long long ans=1;
   int i;
   for (i=n;i>m;i--) ans*=i;
   for (i=n-m;i>1;i--) ans/=i;
   return ans;
}
unsigned long long A(int n,int m)
{
   unsigned long long ans=1;
   int i;
   for (i=n;i>0;i--) ans*=i;
   for (i=n-m;i>1;i--) ans/=i;
   return ans;
}
int main()
{
   char op;
   int n,m,N;
   unsigned long long (*o)(int n,int m);
   for(cin>>N;N--;)
   {
       cin>>op>>n>>m;
       o=(op=='A')?A:C;
       cout<<o(n,m)<<endl;
   }
   return 0;
}