[Solved] Given the following undo and redo stacks after several command... Given the following undo and redo stacks after several command executions and undos, which command was most recently executed? | OOP & Design Patterns

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

Given the following undo and redo stacks after several command executions and undos, which command was most recently executed? undo_stack (top to bottom): [AddCommand(2), AddCommand(5)] redo_stack (top to bottom): [AddCommand(3)]

AAddCommand with value 5

BAddCommand with value 0

CAddCommand with value 2

DAddCommand with value 3

Step-by-Step Solution

Solution:

Step 1: Understand stack order
undo_stack top is last executed command; redo_stack top is last undone command.
Step 2: Identify last executed command
undo_stack top is AddCommand(5), so it was most recently executed.
Final Answer:
Option A -> Option A
Quick Check:
Undo stack top reflects last executed command [OK]

Quick Trick: Undo stack top is last executed command [OK]

Common Mistakes:

MISTAKES

Confusing redo stack top with last executed
Ignoring stack order semantics

Trap Explanation:

PITFALL

Candidates often mistake redo stack top as last executed command, but it holds undone commands.

Interviewer Note:

CONTEXT

Tests deep understanding of undo/redo stack states

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Solution Trace

More OOP & Design Patterns Quizzes

Given the following undo and redo stacks after several command executions and undos, which command was most recently executed?

Step 1: Understand stack order

Step 2: Identify last executed command

Final Answer:

Quick Check:

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