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104 Maximum Depth of Binary Tree.js
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104 Maximum Depth of Binary Tree.js
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https://leetcode.com/problems/maximum-depth-of-binary-tree/submissions/
104. Maximum Depth of Binary Tree
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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.
/**
* 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) {
// use a handler function since it's easier to write and think about recursive code this way. You start at a num/depth value of 1 because of the definition of depth.
return maxDepthHandler(root,1)
};
var maxDepthHandler = function(root, num){
// here's just base case -- if you get an empty root(because you definitely will at some point, just return a depth of zero because there's nothing in the tree!
if(root == null){
return 0
}
// this is your terminating case. a leaf node doesn't have any children, and so the root at that point will have null value. at this point just return the depth/num
if (root.right == null && root.left == null){
return num
}
//Use Math.max to get the highest between the two root depths. the rest of this code is just handling the individual root cases.
if (root.right && root.left){
return Math.max( maxDepthHandler(root.right, num+1), maxDepthHandler(root.left, num + 1))
} else if (root.right != null){
return maxDepthHandler(root.right, num+1)
} else {
return maxDepthHandler(root.left, num+1)
}
};