They added this round because my earlier coding performance was 'mixed', which, fair enough.
Clarify the tree structure (e.g., each node has a list of children) and the traversal order (pre-order). Then implement a recursive DFS that processes the current node and recursively visits each child, or an iterative version using a stack. Discuss trade-offs and test with edge cases.
Pro tip: At Netflix, emphasize how your solution scales to large hierarchies and handles deep recursion without stack overflow, showing you think about production reliability. Mention that you'd consider iterative DFS with an explicit stack for very deep trees.
Ask about the tree representation (e.g., node with children list), the desired traversal order (pre-order, post-order), and whether recursion is acceptable. Confirm input/output expectations.
Decide between recursive and iterative DFS. Recursive is simpler but may cause stack overflow; iterative uses an explicit stack and is safer for deep trees.
Write clean code for the chosen approach. For recursive: process node, then loop through children and recurse. For iterative: use a stack, push children in reverse order to maintain left-to-right traversal.
State time complexity O(n) and space complexity O(h) for recursion (call stack) or O(h) for iterative (explicit stack), where h is tree height. Mention worst-case O(n) for skewed trees.
Walk through examples: empty tree, single node, deep tree, wide tree. Discuss how to handle cycles if the structure is not strictly a tree, and mention potential optimizations.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.