Java Program for Heap Sort

Heap sort is a comparison based sorting technique based on Binary Heap data structure. It is similar to selection sort where we first find the maximum element and place the maximum element at the end. We repeat the same process for remaining element.

Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java program for implementation of Heap Sort
public class HeapSort
{
    public void sort(int arr[])
    {
        int n = arr.length;
  
        // Build heap (rearrange array)
        for (int i = n / 2 - 1; i >= 0; i--)
            heapify(arr, n, i);
  
        // One by one extract an element from heap
        for (int i=n-1; i>=0; i--)
        {
            // Move current root to end
            int temp = arr[0];
            arr[0] = arr[i];
            arr[i] = temp;
  
            // call max heapify on the reduced heap
            heapify(arr, i, 0);
        }
    }
  
    // To heapify a subtree rooted with node i which is
    // an index in arr[]. n is size of heap
    void heapify(int arr[], int n, int i)
    {
        int largest = i;  // Initialize largest as root
        int l = 2*i + 1;  // left = 2*i + 1
        int r = 2*i + 2;  // right = 2*i + 2
  
        // If left child is larger than root
        if (l < n && arr[l] > arr[largest])
            largest = l;
  
        // If right child is larger than largest so far
        if (r < n && arr[r] > arr[largest])
            largest = r;
  
        // If largest is not root
        if (largest != i)
        {
            int swap = arr[i];
            arr[i] = arr[largest];
            arr[largest] = swap;
  
            // Recursively heapify the affected sub-tree
            heapify(arr, n, largest);
        }
    }
  
    /* A utility function to print array of size n */
    static void printArray(int arr[])
    {
        int n = arr.length;
        for (int i=0; i<n; ++i)
            System.out.print(arr[i]+" ");
        System.out.println();
    }
  
    // Driver program
    public static void main(String args[])
    {
        int arr[] = {12, 11, 13, 5, 6, 7};
        int n = arr.length;
  
        HeapSort ob = new HeapSort();
        ob.sort(arr);
  
        System.out.println("Sorted array is");
        printArray(arr);
    }
}

chevron_right






                        filter_none








Please refer complete article on Heap Sort for more details!



          
          
          
          

            

    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts: