Solve Tree Views, Columns, and Calculator

The interview note referenced three separate coding tasks. Solve each task independently. ### Task 1: Binary tree side views Given the root of a binary tree, return two arrays: - `left_view[d]`: the value of the first node visible at depth `d` when looking at the tree from the left side - `right_view[d]`: the value of the first node visible at depth `d` when looking at the tree from the right side Example: - Input tree: - root = 1 - left child = 2, right child = 3 - node 2 has left child 4 - node 3 has right child 5 - Output: `[[1, 2, 4], [1, 3, 5]]` ### Task 2: Group a binary tree by vertical columns Given the root of a binary tree, assign column `0` to the root. For any node at column `c`, its left child is at column `c - 1` and its right child is at column `c + 1`. Return the node values grouped from the leftmost column to the rightmost column. If multiple nodes fall in the same row and column, output them in left-to-right breadth-first order. Example: - Input tree: - root = 3 - left child = 9, right child = 8 - children of 9 are 4 and 0 - children of 8 are 1 and 7 - Output: `[[4], [9], [3, 0, 1], [8], [7]]` ### Task 3: Evaluate a basic arithmetic string Given a string expression containing non-negative integers, spaces, and the operators `+`, `-`, `*`, and `/`, return the evaluated integer result. - Division truncates toward zero. - The expression contains no parentheses. Example: - Input: `"3+2*2"` - Output: `7` Reasonable constraints for all tasks: - Up to `10^5` nodes for tree problems - Expression length up to `10^5`