Lecture Notes on 27 Mar 2013

public class Permute
{
  public static void printArray (int[] a)
  {
    for (int i = 0; i < a.length; i++)
    {
      System.out.print (a[i] + "  ");
    }
    System.out.println();
  }

  public static void swap (int[] a, int k, int i)
  {
    int temp = a[k];
    a[k] = a[i];
    a[i] = temp;
  }

  public static void permute (int[] a, int k)
  {
    if (k == a.length - 1)
      printArray (a);
    else
    {
      for (int i = k; i < a.length; i++)
      {
        swap (a, k, i);
	permute (a, k + 1);
	swap (a, i, k);
      }
    }
  }

  public static void main (String[] args)
  {
    int[] a = {1, 2, 3, 4};
    permute (a, 0);
  }
}