CS Interview Snippets 🧩

A curated collection of small, focused Java and Python code snippets designed for Computer Science & Software Engineering interview preparation.

Instead of large projects, this repository emphasizes clarity, correctness, and conceptual understanding through minimal yet meaningful implementations.

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📌 Why This Repository?

In technical interviews, candidates are evaluated on:

• Core Computer Science fundamentals
• Ability to explain program behavior, not just syntax
• Awareness of common pitfalls, design patterns, and concurrency issues

This repository acts as a personal interview reference containing frequently asked concepts implemented as clean, runnable, and explainable code snippets.

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🧠 Key Philosophy

Each snippet in this repository:

• Demonstrates one interview-relevant concept
• Uses minimal, readable code
• Avoids frameworks and unnecessary boilerplate
• Can be explained verbally within minutes

One concept → One file → Clear explanation

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🗂️ Repository Structure

cs-interview-snippets/ │ ├── java/ │ ├── DeadlockVsStarvation.java │ ├── RaceConditionDemo.java │ ├── Singletonexample.java │ └── ThreadSafetyBasics.java │ ├── python/ │ ├── default_mutable_arguments.py │ ├── gil_demo.py │ ├── mutable_vs_immutable.py │ └── shallow_vs_deep_copy.py │ └── README.md

yaml Copy code

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☕ Java Snippets

1️⃣ Singleton Pattern

File: java/Singletonexample.java

Demonstrates:

• Lazy initialization
• Controlled object creation
• Ensuring a single instance across the application

📌 Interview angle:
Why restrict object creation? How does Singleton differ from static classes?

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2️⃣ Deadlock vs Starvation

File: java/DeadlockVsStarvation.java

Demonstrates:

• Circular lock dependency
• Threads waiting indefinitely
• Difference between deadlock and starvation

📌 Interview angle:
How do deadlocks occur, and how can they be prevented?

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3️⃣ Race Condition

File: java/RaceConditionDemo.java

Demonstrates:

• Multiple threads accessing shared data
• Inconsistent output due to lack of synchronization

📌 Interview angle:
What is a race condition, and how does synchronization solve it?

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4️⃣ Thread Safety Basics

File: java/ThreadSafetyBasics.java

Demonstrates:

• Thread-safe vs non-thread-safe behavior
• Use of synchronization mechanisms

📌 Interview angle:
What makes code thread-safe, and why is it important?

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🐍 Python Snippets

1️⃣ Mutable vs Immutable Objects

File: python/mutable_vs_immutable.py

Demonstrates:

• Behavior of mutable objects (lists)
• Behavior of immutable objects (integers, strings)
• A classic Python interview pitfall

📌 Interview angle:
Why do changes to lists persist outside functions but integers do not?

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2️⃣ Shallow vs Deep Copy

File: python/shallow_vs_deep_copy.py

Demonstrates:

• Reference sharing in shallow copies
• Fully independent objects in deep copies

📌 Interview angle:
Why does modifying a nested object affect a shallow copy?

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3️⃣ Default Mutable Arguments

File: python/default_mutable_arguments.py

Demonstrates:

• How default mutable arguments retain state across function calls
• Why this behavior is dangerous

📌 Interview angle:
Why should mutable objects not be used as default arguments?

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4️⃣ Global Interpreter Lock (GIL)

File: python/gil_demo.py

Demonstrates:

• Python’s Global Interpreter Lock
• Why multi-threading doesn’t always mean parallel execution

📌 Interview angle:
What is the GIL, and how does it affect Python multithreading?

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▶️ Sample Outputs

Singleton Pattern (Java)

true

Deadlock vs Starvation (Java)

(no output – program hangs due to deadlock)

Mutable vs Immutable (Python)

List after modification: [1, 2, 3, 100] Number after modification: 50

Shallow vs Deep Copy (Python)

Original: [[1, 2, 99], [3, 4]] Shallow Copy: [[1, 2, 99], [3, 4]] Deep Copy: [[1, 2], [3, 4]]

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🧠 Learning Outcomes

Through this repository, I aim to:

• Strengthen core CS fundamentals
• Improve interview explanations using real code behavior
• Practice explaining why code behaves the way it does
• Build consistency through small, high-quality commits

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🚀 Future Enhancements

Planned additions:

• Memory visibility & volatile (Java)
• Producer–Consumer problem
• Python multiprocessing vs threading
• JVM vs Python memory model

All future additions will follow the
one-concept-per-file rule.

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⚠️ Note

This repository is intentionally minimal and focused.

It is meant for learning, revision, and interview preparation — not for building production-grade applications.