程序代码：

#include<stdio.h>
#define N 3
#define S(a) sizeof(a)/sizeof(a[0])
int main()
{
    int a[]={1,2,3,4,5,6,7,8,9,10};

    int i=0;
    int j=0;
    
    for (i=0;j!=N*S(a);++i,i%=S(a))
    {
        if (a[i]!=0)
            j++;
        else 
            continue ;
            
        if (j%N==0)
        {
             printf ("%d ",a[i]);
             a[i]=0;
        }
    }
    
    printf("\n");
    
    return 0;
}