Solve the Medium-level Lowest Common Ancestor of a BST coding interview problem online in Python & JavaScript. Run your code against real test cases in the browser and study worked examples. It covers binary tree, binary search tree, and depth first search. Read the step-by-step solution and complexity analysis. Java starter code is also included for reference (no in-browser JVM yet, so it can't be run here).

Lowest Common Ancestor of a BST – Solve Online in Python & JavaScript

Merge Two Sorted Lists

Binary Tree Level Order Traversal

Find the lowest shared ancestor of two values in a binary search tree.

Given a BST and two values present in it, return the value of their lowest common ancestor.

## Example
```json
Input: {"root":[6,2,8,0,4,7,9,null,null,3,5],"p":2,"q":8}
Output: 6
```

## Constraints
- 2 <= number of nodes <= 10000
- All node values are unique
- p and q exist in the tree

## Follow-up
How does BST ordering avoid a full tree traversal?

## Execution note
Java/Go/Rust don't support this problem's ListNode/TreeNode structure yet — the starter is reference-only. Try Python or JavaScript to run and submit.

The key pattern is: BST ordering identifies where search paths split. Identify the state and invariant before coding.

Recognize the Pattern

Advance one state transition at a time. Mark or update state before exploring dependent work.

Build the Algorithm

Test empty or minimal input, skewed shapes, duplicates where allowed, and impossible outcomes.