Matematicki algoritmi - Eratostenovo sito

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    int n;
    cin>>n;

    bool B[n+1];

    for (int i=0;i<=n;i++)
        B[i]=1;

    B[1]=0;
    int sqn=sqrt(n);

    for (int i=2;i<=sqn;i++)
    {
        if (B[i]==0) continue;

        for (int j=i*2;j<=n;j=j+i)
            B[j]=0;
    }

    for (int i=1;i<n+1;i++)
        if (B[i]==1) cout<<i<<' ';
    cout<<endl;

    return 0;
}