Eratosthenes Sieve

#include <iostream>
#include <cmath>
#define MAX 1000000
//eratosthenes sieve
using namespace std;

int primes[MAX+1], n;
void gen_primes(){
    for(int i = 2; i*i <= MAX; i++)
        if(primes[i] == 0)
            for(int j = i*i; j <= MAX; j += i)
                primes[j] = 1;
}
int main(int argc, char** argv) {
    cin>>n;
    gen_primes();
    for(int i = 2; i <= n; i++)
        if(primes[i] == 0)
            cout<<i<<" ";
    cout<<endl;
    return 0;
}