Solve tree, array, and maze tasks

You are given a set of algorithmic problems from a software engineering onsite. 1. **Tree path length**: Given the root of a binary tree, return the number of edges in the longest path between any two nodes in the tree. 2. **Choose two boundaries**: Given an array of non-negative integers where each value is the height of a vertical line at that index, choose two indices `i < j` that maximize `(j - i) * min(height[i], height[j])`. Return the maximum value. 3. **Weighted maze**: Given a 2D grid containing a start cell `S`, a target cell `T`, blocked cells `#`, and non-negative movement costs for traversable cells, compute the minimum total energy required to reach `T` from `S`. Moving into a cell adds that cell's cost. Return `-1` if the target is unreachable. In the later part of this coding interview, the candidate was allowed to use an AI coding assistant after first explaining the intended approach.