**Problem Statement:**
Given the required input arguments, write an efficient algorithm to solve the **Maximum Depth of Binary Tree** problem. Implement the required logic as specified by standard definitions for this classic algorithmic challenge.
**Hint / Expected Approach:**
DFS post-order or BFS level count
**Edge Cases to Consider:**
- (1) Empty tree
- (2) Single node
- (3) Skewed tree (all left or all right)
Examples
Example 1
Input:[3,9,20,null,null,15,7]
Output:3
Explanation: Classic example
Example 2
Input:[1,null,2]
Output:2
Explanation: Right-skewed
Example 3
Input:[]
Output:0
Explanation: Empty tree
Constraints
▪The number of nodes in the tree is in the range [0, 2000]
▪-1000 <= Node.val <= 1000
▪Ensure depth-first or breadth-first traversals are memory-efficient