Maximum Depth / Tree Traversal

Problem

Compute the maximum depth of a tree — the number of nodes along the longest path from the root down to a leaf. The tree may be binary or n-ary (e.g. a nested issue / sub-issue structure).

Input / Output

• Input: the root of the tree (each node holds its children).
• Output: an integer, the maximum depth (0 for an empty tree, 1 for a single root).

Constraints

• Up to 10^4 nodes.
• The tree may be badly skewed (a chain), so a recursive solution risks deep recursion.

Example

      A
     / \
    B   C
        |
        D
max depth = 3   (A -> C -> D)