842. Count Leaf Nodes

EasyTrees Binary Tree DFS Recursion

Given the root of a binary tree, return the number of leaf nodes (nodes with no children). The tree is given as a level-order array with null for missing children.

Input: A level-order array of the tree.

Output: Integer — the leaf count.

Examples

Example 1

Input: [1,2,3,4,5,null,6]
Output: 3
Explanation: Leaves are 4, 5, and 6.

Example 2

Input: [1]
Output: 1
Explanation: Root is a leaf.

Example 3

Input: []
Output: 0
Explanation: Empty tree.

Constraints

0<=nodes<=10^4
-1000<=value<=1000

Asked by

TCS Infosys Wipro Cognizant Capgemini

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