Suppose you need to extend the Composite Pattern iterator to support backtracking (moving backward) in traversal. Which approach fundamentally changes the traversal implementation?

hard🎤 Interviewer Follow-up Q10 of Q15

OOP & Design Patterns - Iterator & Composite Pattern - Traversal Abstractions

AAdding a doubly linked list to store traversal order for backward iteration

BImplementing a bidirectional iterator with two stacks to track forward and backward traversal

CUsing recursion with memoization to remember visited nodes

DSwitching to a breadth-first traversal to simplify backtracking

Step-by-Step Solution

Solution:

Step 1: Understand backtracking requirements
Backward traversal requires ability to revisit previous nodes efficiently.
Step 2: Evaluate approaches
Implementing a bidirectional iterator with two stacks allows tracking forward and backward traversal efficiently.
Step 3: Identify fundamental change
Using two stacks for bidirectional iteration fundamentally changes traversal implementation to support backtracking.
Final Answer:
Option B -> Option B
Quick Check:
Bidirectional iterator with two stacks supports backtracking [OK]

Quick Trick: Backtracking requires bidirectional iterator with two stacks [OK]

Common Mistakes:

MISTAKES

Assuming simple stack tweaks suffice
Ignoring traversal strategy impact
Confusing memoization with traversal order

Trap Explanation:

PITFALL

Candidates underestimate complexity of backward traversal in depth-first iterators.

Interviewer Note:

CONTEXT

Tests candidate's ability to adapt traversal strategy for advanced iterator features.

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Suppose you need to extend the Composite Pattern iterator to support backtracking (moving backward) in traversal. Which approach fundamentally changes the traversal implementation?

Step 1: Understand backtracking requirements

Step 2: Evaluate approaches

Step 3: Identify fundamental change

Final Answer:

Quick Check:

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