EasyTrees
Maximum Depth of Binary Tree
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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:
3
/ \
9 20
/ \
15 7
Input: root = [3,9,20,null,null,15,7]
Output: 3
Example 2:
1
\
2
Input: root = [1,null,2]
Output: 2
Examples
Example 1
Input: root = [3,9,20,null,null,15,7]
Output: 3
Explanation: The tree has 3 levels. The longest path is 3 -> 20 -> 15 (or 3 -> 20 -> 7), which has 3 nodes.
Example 2
Input: root = [1,null,2]
Output: 2
Explanation: The tree has 2 levels. The root is 1, and its right child is 2. The longest path has 2 nodes.
Constraints
- -The number of nodes in the tree is in the range [0, 10^4].
- --100 <= Node.val <= 100
Optimal Complexity
Time
O(n)
Space
O(h)
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