Segmented Sieve of Eratosthenes?

Question

It\'s easy enough to make a simple sieve:

for (int i=2; i<=N; i++){
    if (sieve[i]==0){
        cout << i << \" is prime\" << endl;
           


        

Answer 1

If someone would like to see C++ implementation, here is mine:

void sito_delta( int delta, std::vector &res)
{

std::unique_ptr results(new int[delta+1]);
for(int i = 0; i <= delta; ++i)
    results[i] = 1;

int pierw = sqrt(delta);
for (int j = 2; j <= pierw; ++j)
{
    if(results[j])
    {
        for (int k = 2*j; k <= delta; k+=j)
        {
            results[k]=0;
        }
    }
}

for (int m = 2; m <= delta; ++m)
    if (results[m])
    {
        res.push_back(m);
        std::cout<<","< &fiPri)
{
int delta = sqrt(n);

if (delta>10)
{
    sito_segment(delta,fiPri);
   // COmpute using fiPri as primes
   // n=n,prime = fiPri;
      std::vector prime=fiPri;
      int offset = delta;
      int low = offset;
      int high = offset * 2;
      while (low < n)
      {
          if (high >=n ) high = n;
          int mark[offset+1];
          for (int s=0;s<=offset;++s)
              mark[s]=1;

          for(int j = 0; j< prime.size(); ++j)
          {
            int lowMinimum = (low/prime[j]) * prime[j];
            if(lowMinimum < low)
                lowMinimum += prime[j];

            for(int k = lowMinimum; k<=high;k+=prime[j])
                mark[k-low]=0;
          }

          for(int i = low; i <= high; i++)
              if(mark[i-low])
              {
                fiPri.push_back(i);
                std::cout<<","< prime;
sito_delta(delta, prime);
//
fiPri = prime;
//
int offset = delta;
int low = offset;
int high = offset * 2;
// Process segments one by one 
while (low < n)
{
    if (high >= n) high = n;
    int  mark[offset+1];
    for (int s = 0; s <= offset; ++s)
        mark[s] = 1;

    for (int j = 0; j < prime.size(); ++j)
    {
        // find the minimum number in [low..high] that is
        // multiple of prime[i] (divisible by prime[j])
        int lowMinimum = (low/prime[j]) * prime[j];
        if(lowMinimum < low)
            lowMinimum += prime[j];

        //Mark multiples of prime[i] in [low..high]
        for (int k = lowMinimum; k <= high; k+=prime[j])
            mark[k-low] = 0;
    }

    for (int i = low; i <= high; i++)
        if(mark[i-low])
        {
            fiPri.push_back(i);
            std::cout<<","< fiPri;
sito_segment(1013,fiPri);
}