Question

A perfect binary tree is a complete binary tree with all levels fully filled. Add a method in the BST class to return true if the tree is a perfect binary tree.

Answer 1

Answer:

class BST {

static class Node

{

int val;

Node left, right;

}

static boolean checkPerfectBT(Node node, int h, int d)

{

if (node == null)

return true;

 

if (node.left == null && node.right == null)

{

if(h==d+1)

return true;

else

return false;

}

 

if (node.left == null || node.right== null)

return false;

 

return checkPerfectBT(node.left, h, d+1) && checkPerfectBT(node.right, h, d+1);

}

static int height(Node node)

{

int dep = 0;

while (node != null)

{

node = node.right;

dep=dep+1;

}

return dep;

}

static boolean isPerfectBT(Node node)

{

int h = height(node);

return checkPerfectBT(node, h, 0);

}

 

static Node addNode(int x)

{

Node node = new Node();

node.val= x;

node.right = null;

node.left = null;

return node;

}

public static void main(String args[])

{

int i,j,k;

Node node= null;

node = addNode(34);

node.left = addNode(2);

node.right = addNode(322);

 

node.left.left = addNode(21);

node.left.right = addNode(23);

node.right.left = addNode(37);

node.right.right = addNode(54);

 

if (isPerfectBT(node) == true)

System.out.println("This is a Perfect Binary tree");

else

System.out.println("This is Not a perfect Binary Tree");

}

}

Explanation:

• Calculate the depth of BST by using a while loop until it reaches a null value.
• In the addNode method, make an object of Node class.
• In the main method, pass the values to addNode method.
• Finally display the relevant message to show if it's Perfect or not.