Max Depth

Python data engineering interview problem. Difficulty: advanced. Pattern: Trees. About 18 minutes. Part of the Pro drill bank.

Maximum depth of a binary tree from level-order input. Treat this as a production helper: match the contracted return shape, including empty and duplicate inputs.

A pipeline tree can be shallow or deeply nested. Its depth tells you how many dependency levels a traversal must pass through. Return the maximum number of nodes on a path from the root to a leaf. Decode the level-order list and ignore missing children. Write max_depth(level_order: list) -> int. The tree [3, 9, 20, None, None, 15, 7] has 3 levels, so its depth is 3. The starter file already has the function name and harness print lines. Keep them and fill only the function body.

Requirements

• Count nodes, not edges, on the longest root-to-leaf path.
• Ignore None child slots.
• Return 0 for an empty tree.

Constraints

• The tree is represented in level order and values may be integers.
• The return type is int.

Examples

Input: max_depth([3, 9, 20, None, None, 15, 7]) Output: 3 Root to 15/7 is depth 3.

Topics: lakebench, python, depth, dfs.

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