How do you find the diameter of a Binary Tree?

Difficulty: 6/10

tree traversal, depth-first search, recursive algorithms

Binary Tree Diameter

The diameter is the longest path between any two nodes in the tree. A key observation is that for each node, a candidate diameter passes through that node and has length equal to the height of its left subtree plus the height of its right subtree. A postorder traversal computes subtree heights bottom-up while maintaining the maximum diameter.

javascript

1
Use postorder traversal.
2
Height is computed once for every node.
3
Time complexity: O(n).
4
Auxiliary recursion space: O(h).
5
If diameter is defined in nodes rather than edges, add one to the edge-based result for a non-empty tree.

Scenario Questions

0-2 years experience

2-5 years experience

1Your team is adding a feature that needs the longest path between any two nodes in a binary tree stored in a database. How would you implement the diameter calculation, and what trade‑offs would you consider regarding recursion vs. iterative approaches?

Follow-up Questions