Maximum Depth of a Tree

L7 Medium Trees

Concept

A binary tree is naturally recursive: its depth is one plus the deeper of its two subtrees.

Given the root of a binary tree, return its maximum depth — the number of nodes along the longest path from the root down to the farthest leaf.

Examples

▸ root = [3, 9, 20, nil, nil, 15, 7]

→ 3

▸ root = [1, nil, 2]

→ 2

▸ root = []

→ 0

Progressive Hints

Hint 1 · Nudge

The height of a tree is one more than the taller of its two children's heights.

Hint 2 · Plan

Use the recurrence: the depth of an empty tree is 0, and otherwise it's 1 plus the larger of the left and right depths.

Hint 3 · Approach

If root is nil, return 0. Return 1 + the larger of depth(left) and depth(right).

Output

// Run your code to see the output here.