//01151424 David Karasz

public class Bsp06 {


    public static void main(String[] args) {
        System.out.println("Alle Primzahlen in [m, n]");
        System.out.print("m: ");
        int m = SavitchIn.readInt();
        System.out.println();
        System.out.print("n: ");
        int n = SavitchIn.readInt();
        System.out.println();
        System.out.println(String.format("Alle Primzahlen in [%d, %d]:", m, n));


        boolean[] primes = findPrimes(m, n);
        int primesCount = printPrimes(primes, m);
        System.out.println("Insgesamt " + primesCount + " Primzahlen.");

        System.out.println();
        System.out.println("Sieb des Eratosthenes:");
        System.out.println(String.format("Alle Primzahlen in [%d, %d]:", m, n));
        boolean[] Eratos = sieveOfEratosthenes(n, 0);
        int primesEratos = printPrimes(Eratos, m);
        System.out.println("Insgesamt " + primesEratos + " Primzahlen.");


     }



    public static boolean isPrime(int n) {
           //ueberprueft ob n eine Primzahl ist
              int k = 2;

              while((k <= n) && (n%k != 0) && (n > 1))
                 k++;

              return k == n;
           }


    public static boolean[] findPrimes(int m, int n) {
        if (n < m) return null;
        int size = n - m + 1;
        boolean[] primes = new boolean[size];
        for (int i = m; i <= n; i++) {
            primes[i - m] = isPrime(i);
        }
        return primes;
    }

    public static int printPrimes(boolean[] foundPrimes, int m) {
        int primes = 0;
        for (int i = 0; i < foundPrimes.length; i++) {
            if (foundPrimes[i]) {
                System.out.print(m + i + " ");
                primes++;
            }
        }
        System.out.println();
        return primes;
    }

    public static boolean [] sieveOfEratosthenes(int n, int m){
        boolean [] b = new boolean [n+1];
        if (n == 0)
           b[0] = false;
        if (n == 1)
           b[1] = false;

        for(int i = 0; m <= n; i++, m++){  //m = 0, Werte der Arrays fangen bei 0 an
           b[i] = isPrime(m);
           if(isPrime(m) == true){
              for(int x = 2; x <= n/i; x++){
                 b[i * x] = false;
              }
           }
        }

        return b;
     }

}