LLD - Behavioral Design Patterns — Part 1
When designing an iterator for a tree structure to traverse nodes in depth-first order, which design best aligns with the Iterator pattern?
When designing an iterator for a tree structure to traverse nodes in depth-first order, which design best aligns with the Iterator pattern?
hard📝 Trade-off Q8 of 15
Step-by-Step Solution
Solution:
Step 1: Understand Iterator pattern goal
The pattern encapsulates traversal logic inside the iterator, hiding internal structure.Step 2: Evaluate options
Implement a stack-based iterator that manages traversal state internally uses a stack-based iterator managing traversal internally, fitting the pattern. Options B and C expose internals or push traversal to clients. Flatten the tree into a list before iteration breaks encapsulation by flattening upfront.Final Answer:
Implement a stack-based iterator that manages traversal state internally -> Option DQuick Check:
Iterator encapsulates traversal, not exposes or delegates it [OK]
Quick Trick: Iterator hides traversal logic inside, uses stack for DFS [OK]
Common Mistakes:
MISTAKES- Exposing internal tree structure to clients
- Using client-side recursion instead of iterator
- Pre-flattening tree breaking encapsulation
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