素筛模板

#include<iostream>
#include<cstring>

#define MAX_N 10000000

using namespace std;

bool flag[MAX_N];
int prime[MAX_N];

void solve()
{
    memset(flag,1,sizeof(flag));
    flag[1] = 0;
    int con=0;
    for(int i = 2; i < MAX_N; i++)
    {
        if(flag[i])
        {
            prime[con++] = i;
            for(int j = 2*i; j < MAX_N; j+=i)
                flag[j] = 0;
        }
    }
}
int main()
{
    solve();
    return 0;
}