Heap Sort Algorithm in Java Programming

Heap Sort Algorithm

Heap Sort Algorithm example in Java programming :

public class HeapSort {
   
  public static void main(String a[]) {
     
    int i;
    int arr[] = { 1, 3, 4, 5, 2 };

    System.out.println("\nHeap Sort\n---------------");
    System.out.println("\nUnsorted Array\n---------------");
     
    for (i = 0; i < arr.length; i++){
       
      System.out.print(" " + arr[i]);
       
    }
     
    for (i = arr.length; i > 1; i--) {
       
      fnSortHeap(arr, i - 1);
       
    }
     
    System.out.println("\n\nSorted array\n---------------");
     
    for (i = 0; i < arr.length; i++){
       
      System.out.print(" " + arr[i]);
       
    }
       
  }

  public static void fnSortHeap(int array[], int arr_ubound) {
     
    int i, o;
    int lChild, rChild, mChild, root, temp;
     
    root = (arr_ubound - 1) / 2;

    for (o = root; o >= 0; o--) {
       
      for (i = root; i >= 0; i--) {
         
        lChild = (2 * i) + 1;
        rChild = (2 * i) + 2;
         
        if ((lChild <= arr_ubound) && (rChild <= arr_ubound)) {
           
          if (array[rChild] >= array[lChild])
            mChild = rChild;
          else
            mChild = lChild;
           
        } else {
           
          if (rChild > arr_ubound)
            mChild = lChild;
          else
            mChild = rChild;
           
        }

        if (array[i] < array[mChild]) {
           
          temp = array[i];
          array[i] = array[mChild];
          array[mChild] = temp;
           
        }
      }
    }
     
    temp = array[0];
    array[0] = array[arr_ubound];
    array[arr_ubound] = temp;
    return;
     
  }
}

OUTPUT

Heap Sort
---------------
Unsorted Array
---------------
1 3 4 5 2
Sorted array
---------------
1 2 3 4 5