BFS was the obvious move and I got there, but I wasted probably 10 minutes fumbling with parsing the input string into an actual tree.
Clarify the input format and edge cases, then use BFS with a queue to process nodes level by level, computing the average for each level. Handle nulls appropriately by only enqueuing non-null children, and ensure integer division is avoided by using floating-point sums.
Pro tip: Mention that you can avoid storing all nodes by processing level by level with a queue, and discuss how to handle large trees to avoid integer overflow by using a double for the sum.
Ask about the input format (e.g., array representation, null handling), output format (space-separated averages), and edge cases (empty tree, negative values).
Use a queue to traverse the tree level by level. Initialize the queue with the root if it's not null.
For each level, record the number of nodes, sum their values, and enqueue their non-null children. Compute the average as sum / count.
Collect the averages in a list and print them space-separated, ensuring proper formatting (e.g., rounding to a reasonable number of decimal places).
Discuss time and space complexity (O(n) time, O(w) space where w is max width), and mention handling of empty tree, single node, and skewed tree.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.