Question

answer in java

Given a Binary Search Tree containing integer values, write a method to print the values in descending order. public class Treenode { int val; Treenode left; Treenode right; Treenode (int x) { val = x; } The method signature is: public void reverseSorted(Treenode root){ // your code

Answer 1

> Printing BST in descending order can be done using reverse inorder traversal of BST.
Let us take an example to understand the solution.

  

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This is a Binary Search Tree and following will be the inorder and reverse inorder of above binary search tree

• Inorder (Left Root Right) ---> 1 2 3
• Reverse Inorder (Right Root Left) ----> 3 2 1

As you can observe that Reverse Inorder of BST gives us nodes in descending order.

Code:

 public void reverseSorted(Treenode root){          
     //Check if root is null or not, if null then return            
     if(root == null)                       
        return;                                 

     //recursively call Right node first            
     reverseSorted(root.right);              

     //Print data of the root node      
     System.out.print(root.val+" ");           

     //At last, recursively call the Left node   
     reverseSorted(root.left);       
}

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