Heap Sort for decreasing order using min heap | Java program for implementation of Heap Sort ; To heapify a subtree rooted with node i which is an index in arr [ ] . n is size of heap ; Initialize smalles as root ; left = 2 * i + 1 ; right = 2 * i + 2 ; If left child is smaller than root ; If right child is smaller than smallest so far ; If smallest is not root ; Recursively heapify the affected sub - tree ; main function to do heap sort ; Build heap ( rearrange array ) ; One by one extract an element from heap ; Move current root to end ; call max heapify on the reduced heap ; A utility function to print array of size n ; Driver program
import java . io . * ; class GFG { static void heapify ( int arr [ ] , int n , int i ) { int smallest = i ; int l = 2 * i + 1 ; int r = 2 * i + 2 ; if ( l < n && arr [ l ] < arr [ smallest ] ) smallest = l ; if ( r < n && arr [ r ] < arr [ smallest ] ) smallest = r ; if ( smallest != i ) { int temp = arr [ i ] ; arr [ i ] = arr [ smallest ] ; arr [ smallest ] = temp ; heapify ( arr , n , smallest ) ; } } static void heapSort ( int arr [ ] , int n ) { for ( int i = n / 2 - 1 ; i >= 0 ; i -- ) heapify ( arr , n , i ) ; for ( int i = n - 1 ; i >= 0 ; i -- ) { int temp = arr [ 0 ] ; arr [ 0 ] = arr [ i ] ; arr [ i ] = temp ; heapify ( arr , i , 0 ) ; } } static void printArray ( int arr [ ] , int n ) { for ( int i = 0 ; i < n ; ++ i ) System . out . print ( arr [ i ] + " ▁ " ) ; System . out . println ( ) ; } public static void main ( String [ ] args ) { int arr [ ] = { 4 , 6 , 3 , 2 , 9 } ; int n = arr . length ; heapSort ( arr , n ) ; System . out . println ( " Sorted ▁ array ▁ is ▁ " ) ; printArray ( arr , n ) ; } }