Construct a BST and read spiral order

The coding round reportedly included two algorithmic tasks: 1. **Rebuild a binary search tree from a preorder sequence** - You are given an array of distinct integers representing the preorder traversal of a binary search tree. - Reconstruct the original tree and return its root. - Aim for a solution that runs in linear time. 2. **Traverse a matrix in clockwise layers** - You are given an `m x n` integer matrix. - Return all elements in the order obtained by repeatedly visiting the current outer boundary clockwise and then shrinking the boundary until every cell has been visited.