[Solved] Given the following Python code using deep copy, what will be printed after modifying... Given the following Python code using deep copy, what will be printed after modifying the copy's scores list? | OOP & Design Patterns

OOP & Design Patterns - Prototype Pattern - Deep Copy vs Shallow Copy

Given the following Python code using deep copy, what will be printed after modifying the copy's scores list?

import copy

class Profile:
    def __init__(self, name, scores):
        self.name = name
        self.scores = scores

    def __deepcopy__(self, memo):
        new_name = copy.deepcopy(self.name, memo)
        new_scores = copy.deepcopy(self.scores, memo)
        return Profile(new_name, new_scores)

original = Profile('Alice', [10, 20])
copy_obj = copy.deepcopy(original)
print('Original scores:', original.scores)
print('Copy scores:', copy_obj.scores)
copy_obj.scores.append(30)
print('After modifying copy scores:')
print('Original scores:', original.scores)
print('Copy scores:', copy_obj.scores)

AOriginal scores: [10, 20] Copy scores: [10, 20] After modifying copy scores: Original scores: [10, 20, 30] Copy scores: [10, 20, 30]

BOriginal scores: [10, 20] Copy scores: [10, 20] After modifying copy scores: Original scores: [10, 20] Copy scores: [10, 20, 30]

COriginal scores: [10, 20] Copy scores: [10, 20] After modifying copy scores: Original scores: [10, 20] Copy scores: [10, 20]

DOriginal scores: [10, 20] Copy scores: [10, 20, 30] After modifying copy scores: Original scores: [10, 20] Copy scores: [10, 20, 30]

Step-by-Step Solution

Step 1: Trace initial print statements
Both original.scores and copy_obj.scores start as [10, 20], so first two prints show identical lists.
Step 2: Trace modification and final prints
copy_obj.scores.append(30) modifies only the copy's scores list because deep copy created a new list. Original remains [10, 20]. Final prints reflect this separation.
Final Answer:
Option B -> Option B
Quick Check:
Deep copy prevents shared nested list -> original unchanged [OK]

Quick Trick: Deep copy isolates nested mutable objects [OK]

Common Mistakes:

MISTAKES

Assuming append affects original due to shared reference

Trap Explanation:

PITFALL

Candidates often think copy_obj.scores shares reference, so original changes too.

Interviewer Note:

CONTEXT

Checks candidate's ability to mentally execute deep copy behavior on nested mutable fields.

Master "Prototype Pattern - Deep Copy vs Shallow Copy" in OOP & Design Patterns

2 interactive learning modes - each teaches the same concept differently

Solution Trace

More OOP & Design Patterns Quizzes

Given the following Python code using deep copy, what will be printed after modifying the copy's scores list?

Step 1: Trace initial print statements

Step 2: Trace modification and final prints

Final Answer:

Quick Check:

Want More Practice?