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104. Maximum Depth of Binary Tree
Easy
Given the root of a binary tree, return its maximum depth.
A binary tree’s maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
Example 1:
Input: root = [3,9,20,null,null,15,7]
Output: 3
Example 2:
Input: root = [1,null,2]
Output: 2
Example 3:
Input: root = []
Output: 0
Example 4:
Input: root = [0]
Output: 1
Constraints:
- The number of nodes in the tree is in the range
[0, 104]. -100 <= Node.val <= 100
Solution
import { TreeNode } from '../../com_github_leetcode/treenode'
/*
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
function maxDepth(root: TreeNode | null): number {
let max = 1
if (!root) {
return 0
}
const rec = (node: TreeNode | null, depht: number): void => {
max = Math.max(max, depht)
if (!node) {
return
}
if (node.left) {
rec(node.left, depht + 1)
}
if (node.right) {
rec(node.right, depht + 1)
}
}
rec(root, 1)
return max
}
export { maxDepth }