PrimeSieve.java

public class PrimeSieve

 public static void main(String[] args)

        int N = Integer.parseInt(args[0]);

                     boolean[] isPrime = new boolean[N + 1];

        for (int i = 2; i <= N; i++)

            isPrime[i] = true;

                     for (int i = 2; i*i <= N; i++)

                        if (isPrime[i])

                for (int j = i; i*j <= N; j++)

                    isPrime[i*j] = false;

                      int primes = 0;

        for (int i = 2; i <= N; i++)

            if (isPrime[i]) primes++;

        System.out.println("The number of primes <= " + N + " is " + primes);

SelfAvoidingWalk.java

public class SelfAvoidingWalk

 public static void main(String[] args)

        int N = Integer.parseInt(args[0]);

        int T = Integer.parseInt(args[1]);

        int deadEnds = 0;

                        for (int t = 0; t < T; t++)

            boolean[][] a = new boolean[N][N];

            int x = N/2, y = N/2;

                         while (x > 0 && x < N-1 && y > 0 && y < N-1)

            if (a[x-1][y] && a[x+1][y] && a[x][y-1] && a[x][y+1])

                    deadEnds++;

                    break;

                a[x][y] = true;

                double r = Math.random();

                if      (r < 0.25) { if (!a[x+1][y]) x++;

                else if (r < 0.50) { if (!a[x-1][y]) x--;

                else if (r < 0.75) { if (!a[x][y+1]) y++;

                else if (r < 1.00) { if (!a[x][y-1]) y--;

        System.out.println(100*deadEnds/T + "% dead ends");

public class RandomSeq

 public static void main(String[] args)

                        int N = Integer.parseInt(args[0]);

       for (int i = 0; i < N; i++)

            System.out.println(Math.random());