Count the Leaves!

Write a function to find the total number of leaf nodes in a binary tree. A node is described as a leaf node if it doesn't have any children. If there are no leaf nodes, return 0.

Example:  
       1
      / \
     2   3     
    / \ / \
   4  5 6  7
  / \
 8   9     
==> no. of leaves = 5

Need a hand? Try out these hints, one at a time.

Quick hint to get things rolling

A recursive implementation is straightforward.

Final hint! You should be able to code the problem on viewing this.

1. Recursively traverse the tree.
2. At each node, determine if its left and right child nodes are null.
2a. If true, return 1.
2b. Otherwise, find number of leaves in its left and right subtrees (recursively).
3. Return the sum of the number of leaves in the left and the right subtrees.

public int numberOfLeaves(TreeNode root) { 
    



}

This Coding Interview Question is available with an answer in the following programming languages :

Java

Python

Count the Leaves!

Quick hint to get things rolling

Final hint! You should be able to code the problem on viewing this.

The interview prep tool you'll fall in love with!

This Coding Interview Question is available with an answer in the following programming languages :