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The traversal itself wasn't the hard part.
Use depth-first search (DFS) with backtracking to traverse the tree, maintaining the current path as a list of node values. When a leaf is reached, convert the path to a string joined by '->' and add it to the result. This approach is efficient and straightforward for enumerating all root-to-leaf paths.
Pro tip: Mention that you would clarify edge cases upfront, such as an empty tree or a single-node tree, and discuss the trade-offs between recursive and iterative solutions. This shows attention to detail and practical engineering maturity.
Confirm the definition of a leaf (node with no children) and ask about handling an empty tree. Discuss expected output format and any constraints.
Select DFS with backtracking for its simplicity and natural fit for path tracking. Alternatively, consider BFS with a queue of paths, but note DFS is more space-efficient for deep trees.
Write a helper function that takes a node and the current path. If the node is a leaf, format the path as a string and add to results. Otherwise, recurse on left and right children, appending the current node's value to the path before each recursive call and backtracking after.
State that time complexity is O(N) for visiting each node once, and space complexity is O(H) for recursion stack plus O(N*H) for output storage in the worst case. Walk through a small example to verify correctness.
Mention iterative approaches using an explicit stack, or how to adapt the solution if paths need to be returned as lists instead of strings. Highlight any trade-offs.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.