static_facs_continue.cpp

几种计算阶乘、阶乘之和的算法

#include<stdio.h>
#define forever for(;;)
int fac(int n);
int sum(int n); 
int function(int n);

void main()
{   forever
{	 
	
    	int n1,n2,k=1,j=0,y;
    	printf("In put a N:");
		if(k>j)
		{
    	scanf("%d",&n1);
		j++;
		}
		else
		{scanf("%d",&n2);
	     k++;
		}
		if(k==1)
		{
			y=function(n1);
			printf("%d\n",y);
			
		}
		else
		{
		    if(k>j)
			{
		    	y=function(n2)-function(n1);
	        	printf("%d\n",y);
			   
			}
	    	else
			{
		    	y=function(n1)-function(n2);
		        printf("%d\n",y);
				
			}
		}
		sum(-1);
}

} 


int function(int n)
{
	int j;
	while(n>0)	
	{
	      sum(n); 	
	    	n--;
		}
	j=sum(0);

	return j;
}


int sum(int n)
{	static int s;
if(n==-1)
s=0;
else
{s+=fac(n);
return s;}
}


int fac(int n) 
{if(n==0)
return 1; 
else 
return n*fac(n-1);
}