hdu1262寻找素数对<数论>

链接:http://acm.hdu.edu.cn/showproblem.php?pid=1262

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int a[10005]={0};
void fun(  )
{
    a[1]=a[0]=1;
    for( int i=4; i<10005; i+=2 )
        a[i]=1;
    for( int i=3; i <= ( int )sqrt( 10005 ); i+=2 )
    {
        if(a[i]==0)
            for( int j=i*i; j<10005; j += ( i+i ) )    
            {
                a[j]=1;    
            }
    }      
}

int main()
{
    fun( );
    int n;
    while( scanf( "%d", &n ) != EOF )
    {
        for( int i=n/2; i>1; i-- )
        {
            if( a[i]==0 && a[n-i]==0 )
            {
                    printf( "%d %d\n", i, n-i );
                break;    
            }        
        }    
    }
    return 0;
}