题解 | 筛选法求素数

#include <stdio.h>
#include<math.h>
int main() {
    //输入
    int n ;
    int count = 0;
    int arr[100] = {0};
    while((scanf("%d",&n)) == 1)
    {
        for(int i = 2; i <= n; i++)
        {
            arr[i] = i;
        }
        for(int i = 2; i <= n; i++)
        {
            int j = 0;
            for(j = 2; j <= (int)sqrt(i);j++)
            {
                if(i%j == 0)

                {
                    arr[i] = 0;
                }
            }
        }
        for(int i = 2; i <= n; i++)
        {
            if(arr[i] != 0)
            {
                printf("%d ",arr[i]);
            }
            else {
                count++;
            }
        }
            printf("\n%d",count);

    }
    return 0;
}