# How to find height or maximum depth of binary of binary tree ?

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Note: A leaf is a node with no children.

Example:

Given binary tree [3,9,20,null,null,15,7],

3

/ \

9 20

/ \

15 7

return its depth = 3.

noob Answered question

Here is a simple Javascript algorithm to achieve the same.

**Steps**

- Traverse and find height of left subtree.
- Traverse and find height of right subtree.
- Find max between heights of left and right subtrees.
- return the max height + 1 (for root node).

**Javascript code:-**

/** * Definition for a binary tree node. * function TreeNode(val) { * this.val = val; * this.left = this.right = null; * } */ /** * @param {TreeNode} root * @return {number} */ var maxDepth = function(root) { if (root === null) return 0; return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1; };

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