运行时间和下式成正比：N+N/2+N/3+N/7+N/11+……
#include <cstdio>
#include <cstdlib>
using namespace std;
int main(int argc, char* argv[])
{
int n;
if (argc != 2)
{
printf("usage:bin n
");
exit(0);
}
n = atoi(argv[1]);
int i;
int* arr = (int *)malloc(sizeof(int)*(n+1));
for (i = 0; i <= n; i++)
arr[i] = 1;
int j;
for (i = 2; i <= n; i++)
{
if (arr[i]!=0)
for (j = i; j*i <= n;j++)
arr[i*j] = 0;
}
for (i = 2; i <= n;i++)
if (arr[i])
printf("%d ",i);
printf("
");
return 0;
}
指定参数为100后，得到100以内的质数，如下：
