Loading problem

Diameter of Binary Tree

Given the root of a binary tree, return its diameter: the number of edges on the longest path between any two nodes. The path need not pass through the root.

Figure

level order, nulls omitted

Examples

in: root = [1,2,3,4,5]

out: 3

path 4 -> 2 -> 1 -> 3 or 5 -> 2 -> 1 -> 3

Constraints

0 <= number of nodes <= 10^4
-100 <= node value <= 100

Hints

target: O(n) time⌘↩ run · ⇧⌘↩ submit