infoarena informatica de performanta

//class PrimeNumbersSieve1
  final int MAXSIZE = 1000001;
  char[] p = new char[MAXSIZE];
  //p[i] == 0 if i is prime
  public int getTheNumber(int n) {
    int i, j, nr = 0;
    for (i = 2; i <= n; ++i) {
      if (p[i] == 0) {
        nr++;
        for (j = i + i; j <= n; j += i) {
          p[j] = 1;
        }
      }
    }