> 先是wa的代码：
> #include <stdio.h>
> 
> double fun(unsigned long k,unsigned int n)
> {
> 	double result;
> 	double res=1.0;
> 	unsigned long i=1;
> 	if(k==0)  result=1;
> 	else
> 	{
> 	while(i<=k)
> 	{
> 		res/=i;
> 		res*=(n-i+1);
> 		i++;
> 	}
> 	result=res;
> 	}
> 	return result;
> }
> 
> int main()
> {
> 	unsigned long n,k;
> 	scanf("%ld %ld",&n,&k);
> 	while(n)
> 	{
> 		double result;
> 		if(k>n/2) result=fun(n-k,n);
> 		else result=fun(k,n);
> 		printf("%d\n",(int)result);－－－－－用%d\n,(int)result
> 	    scanf("%ld %ld",&n,&k);
> 	}
> 	return 0;
> }
> 
> 接下来是ac的代码：
> 
> #include <stdio.h>
> 
> double fun(unsigned long k,unsigned int n)
> {
> 	double result;
> 	double res=1.0;
> 	unsigned long i=1;
> 	if(k==0)  result=1;
> 	else
> 	{
> 	while(i<=k)
> 	{
> 		res/=i;
> 		res*=(n-i+1);
> 		i++;
> 	}
> 	result=res;
> 	}
> 	return result;
> }
> 
> int main()
> {
> 	unsigned long n,k;
> 	scanf("%ld %ld",&n,&k);
> 	while(n)
> 	{
> 		double result;
> 		if(k>n/2) result=fun(n-k,n);
> 		else result=fun(k,n);
> 		printf("%.0f\n",result);－－－－用的是%.0f\n,result
> 	    scanf("%ld %ld",&n,&k);
> 	}
> 	return 0;
> }
> 
> 这二者之间有什么区别吗？请高手相告!!
> 
> 
>