import java.applet.*;
import java.awt.*;

public class MergeSortDemo extends Applet {

  final static int arraySize = 30;
  static float tempArray[] = new float[arraySize];

  public void paint(Graphics g) {

    int i;
    float array[] = new float[arraySize];


    for (i=0;i<arraySize;i++) array[i] = arraySize-i;
    g.drawString("Before sorting", 0, 20);
    printArray(g, array, 40);

    mergeSort(array, 0, arraySize-1);

    g.drawString("After Sorting", 0, 60);
    printArray(g, array, 80);

  }

  private void mergeSort(float[] array, int firstElement, int lastElement) {

    int   midpoint;
    float tempArray[] = new float[lastElement - lastElement];

    if (firstElement<lastElement) {

      midpoint = ((firstElement + lastElement) / 2);
      mergeSort(array,firstElement, midpoint);
      mergeSort(array,midpoint+1,lastElement);
      merge(array, firstElement, midpoint, lastElement); 

    }

  }

  private void merge(float[] array, int firstElement, int midpoint,
                                                      int lastElement) {

    int   i, j, k;

    i = firstElement;
    j = midpoint+1;
    k = firstElement;

    do {

      if (j==lastElement+1 || array[i]<array[j]) 
        tempArray[k++] = array[i++];
      else
        tempArray[k++] = array[j++]; 

    } while (k<=lastElement);

    for (i=firstElement;i<=lastElement;i++) {
      array[i] = tempArray[i];
    }

  }

  private void printArray(Graphics g, float[] array, int y) {

    int i;

    for (i=0;i<arraySize;i++) g.drawString(array[i] + " ", 30*i, y);

  }

}