[Solved] Suppose you want to extend the Command Pattern to support multi-level undo/redo with branching... Which data structure change fundamentally alters the approach and requires a different design? | OOP & Design Patterns

OOP & Design Patterns - Command Pattern - Undo/Redo, Request Queuing & Logging

Suppose you want to extend the Command Pattern to support multi-level undo/redo with branching histories (i.e., multiple redo paths after undo). Which data structure change fundamentally alters the approach and requires a different design?

AUse a tree or graph structure to represent branching command histories

BUse a doubly linked list to store commands linearly

CStore commands in a hash map keyed by command ID

DReplace undo and redo stacks with a single queue

Step-by-Step Solution

Solution:

Step 1: Understand branching undo/redo requirements
Branching histories require tracking multiple redo paths after undo.
Step 2: Identify suitable data structure
A tree or graph structure models branching histories; hash map alone does not represent order or branches.
Step 3: Evaluate options
Queue and doubly linked list are linear, insufficient for branching; hash map is for fast lookup, not history structure.
Final Answer:
Option A -> Option A
Quick Check:
Branching undo/redo requires tree/graph, not linear or hash map alone [OK]

Quick Trick: Branching histories need tree/graph, not linear or hash map [OK]

Common Mistakes:

MISTAKES

Choosing linear structures for branching undo
Confusing hash map with history structure

Trap Explanation:

PITFALL

Candidates often pick hash map for fast access but miss that it doesn't model branching history order.

Interviewer Note:

CONTEXT

Tests ability to adapt Command Pattern for complex undo/redo scenarios

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Solution Trace

More OOP & Design Patterns Quizzes

Which data structure change fundamentally alters the approach and requires a different design?

Step 1: Understand branching undo/redo requirements

Step 2: Identify suitable data structure

Step 3: Evaluate options

Final Answer:

Quick Check:

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