HDU1319 & PKU3518 - Prime Cuts

#include<iostream>
using namespace std;

int list[1010]={0,1,2,3};

int Find(int N)                   //  N       
{
	int i;
	for(i=1;i<=1000;i++)
		if(N<list[i])                    
		{
			i--;
			break;
		}
	
	return i;                     //    1000       ，    1000    N    ， 
	                              //              1000        1000   
								  //      1100 ，AC 
}

bool Isprime(int n)               //     
{
     int i = 0;
     for(i = 2; i < n; i++)
     if(n % i == 0)
     return false;
     return true;
} 

int main()
{
	int i,j,k,N,C,c,center,begin;
	for(k=i=4;i<=1100;i++)                          //1100  1000   
		if( Isprime(i) )
			list[ k++ ] = i ;
	
	while( scanf("%d%d",&N,&C)!=EOF )
	{
		int F = Find(N);                           //      
		center = F/2;                              //   
		if( F%2==0 )
		{
			c = 2 * C ;                            //c         
			begin = center-C+1;
		}
		else
		{
			c=2*C-1;
			begin=center-(C-1)+1;
		}
		
		//printf("F=%d c=%d center=%d begin=%d
",F,c,center,begin);
		
		printf("%d %d:",N,C);
		
		if(F<c)
			for(i=1;i<=F;i++)
				printf(" %d",list[i]);
		else
			for(i=begin,j=1;j<=c;j++,i++)
				printf(" %d",list[i]);

		printf("

");
	}
	return 0;
}