This one took me longer than it should have to get started.
Start by clarifying requirements and constraints, then propose a tree data structure where each node is either a leaf (pane) or an internal node with a direction and two children. Implement split by locating the leaf with the given viewId and replacing it with a new internal node containing the original leaf and a new leaf. For toString, recursively serialize the tree with consistent formatting, ensuring deterministic output by sorting or using a fixed traversal order.
Pro tip: Mention that you would use a recursive approach for both split and toString, and that you'd consider edge cases like splitting a non-existent viewId or handling nested splits. Also, discuss how you might optimize for frequent splits by using a map from viewId to node for O(1) lookup.
Ask about the expected input/output format, whether viewIds are unique, and if there are any performance requirements. Confirm that the tree should be binary and that splits are always into two panes.
Define a Node class with type (leaf or internal), viewId (for leaves), direction (for internal), and left/right children. Consider maintaining a map from viewId to node for efficient lookup.
Traverse the tree to find the leaf with viewId. Replace it with an internal node of the given direction, with the original leaf as one child and a new leaf as the other. Update the map accordingly.
Recursively generate a string representation. For leaves, output the viewId; for internal nodes, output the direction and recursively include children, using parentheses or indentation to show structure. Ensure deterministic order (e.g., always left then right).
Walk through examples, including nested splits. Discuss time complexity (O(n) for split without map, O(1) with map) and space complexity. Mention potential improvements like balancing or different traversal orders.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.