1938.cpp

浙大acm在线评判系统zju online judge上面的题目解答源码（1）

#include<iostream.h>


unsigned long long c(unsigned long long n,unsigned long long k);
int main()
{
  unsigned long long n,k;
  while(cin>>n>>k)
  {
    if(n==0&&k==0) break;
 if(k>n/2) k=n-k;
   cout<<c(n,k)<<endl;
    }
    return 0;
}


unsigned long long c(unsigned long long n,unsigned long long k)
{ unsigned long long s=1;
  int i;
 for(i=1;i<=k;i++) 
  s=s*(n-k+i)/i; 
 
  return s;
  }