Use a stack to process each component of the path, handling '.' and '..' appropriately. Split the path by '/', iterate through components, and build the canonical path by pushing valid directory names and popping for '..'. Finally, join the stack with '/' and prepend a leading slash.
Pro tip: Clarify edge cases upfront, like paths with only slashes or multiple '..' at the root, and mention that you'll handle them without errors. Also, discuss how your solution avoids unnecessary string concatenations for efficiency.
Confirm the definition of canonical path: absolute, no '.' or '..', no consecutive slashes, no trailing slash (except root). Ask about edge cases like empty string, root path, and paths with multiple '..' that go above root.
Explain that a stack is ideal for processing path components because it naturally handles '..' by popping the last directory. Outline the algorithm: split by '/', iterate, skip empty and '.', pop for '..', push otherwise.
Trace through examples like '/home//foo/' and '/../' to demonstrate handling of consecutive slashes, trailing slashes, and '..' at root. Show how the stack evolves and the final result is constructed.
State that time complexity is O(n) where n is the length of the path, as each character is processed once. Space complexity is O(n) for the stack and the output string in the worst case.
Mention that you can avoid splitting into an array by scanning the string and building components on the fly, reducing space. Also, note that the root path '/' is a special case where the stack is empty.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Start by clarifying the nested list structure and the iterator interface, then propose a lazy stack-based solution that maintains a stack of iterators or lists to handle arbitrary depth. Walk through the algorithm for hasNext() and next(), and optionally discuss an eager flattening approach using recursion or a stack. Finally, compare the tradeoffs between lazy and eager designs in terms of time/space complexity, memory usage, and suitability for different scenarios.
Pro tip: Emphasize that the lazy approach is more memory-efficient for large or infinite nested structures and avoids unnecessary traversal, but the eager approach can be simpler and faster if the entire structure is small and needs to be traversed multiple times.
Ask about the nested list structure (e.g., can it be modified during iteration? what are the expected sizes?) and the iterator interface (hasNext, next, remove?).
Use a stack to keep track of iterators or lists at each level. In hasNext(), peek and advance until an integer is found or stack is empty. In next(), return the next integer.
Write pseudocode or actual code for the lazy iterator, and trace through a sample nested list to demonstrate correctness.
Describe how to pre-flatten the nested list into a single list of integers using recursion or an explicit stack, and then iterate over that list.
Analyze time and space complexity, memory usage, and use cases for both approaches. Mention that lazy is better for large/infinite structures, while eager is simpler and faster for small, static structures.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.