Understanding Tree Maximum Depth
Return the number of nodes on the longest path from the root of a binary tree to a leaf. The input uses level-order values with null for missing children.
How it works
The answer at each node depends only on the depths returned by its two children.
The base case returns zero for null. Each non-null call returns one plus the larger child depth. The call stack stores unfinished parent work.
Try an example
Input: values = [3, 9, 20, null, null, 15, 7]
Output: 3
The path 3 → 20 → 15 contains three nodes.
Constraints
- An empty tree has depth 0.
- A single-node tree has depth 1.
- Visualization limit: 63 level-order entries.
Use the simulator
Change the input, then choose Visualize input. Use Next and Previous to inspect each decision, or Play to advance automatically. Compare approaches and their complexity. Choose Try yourself to write JavaScript, select My code and Visualize code to inspect its execution, or Run Tests to check results.
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