HS Computer Science (Intro) practice questions and exam guide

Big-O notation describes:

1. Asymptotic upper bound of algorithm runtime — worst-case growth as input grows
2. Best-case
3. Random
4. Has no purpose

Answer: A — Asymptotic upper bound of algorithm runtime — worst-case growth as input grows

A) Standard. B/C/D) Each is incorrect.

Generative AI:

1. Models that create new content (text, images, code, music) based on training data — large language models (LLMs like GPT, Claude, Llama), image generators (Stable Diffusion, DALL-E), code assistants; transformative for productivity but raise concerns about accuracy (hallucinations), bias, copyright, education, jobs, misinformation, and consent
2. Has no real use
3. Only generates text
4. Always factual

Answer: A — Models that create new content (text, images, code, music) based on training data — large language models (LLMs like GPT, Claude, Llama), image generators (Stable Diffusion, DALL-E), code assistants; transformative for productivity but raise concerns about accuracy (hallucinations), bias, copyright, education, jobs, misinformation, and consent

A) Standard. B/C/D) Each is incorrect.

A phishing attack most commonly tries to:

1. Overload servers with traffic
2. Encrypt files for ransom
3. Trick users into revealing credentials via deceptive messages
4. Crack passwords by brute force

Answer: C — Trick users into revealing credentials via deceptive messages

C) Social engineering — fake emails/sites. A) That's DDoS. B) That's ransomware. D) That's brute-force cracking.

Hardware vs. software:

1. Same thing
2. Hardware is virtual
3. Both same
4. Software is physical
5. Hardware = physical components (CPU, RAM, drives, peripherals); Software = programs and data running on hardware (OS, applications, code)

Answer: E — Hardware = physical components (CPU, RAM, drives, peripherals); Software = programs and data running on hardware (OS, applications, code)

Hardware: tangible. Software: intangible (instructions for hardware). Firmware: software embedded in hardware (BIOS, IoT firmware). OS bridges hardware and applications. CPU executes machine code (compiled or interpreted from higher-level code).

In most programming languages, what does '==' typically do?

1. Assigns a value to a variable
2. Compares two values for equality and returns a boolean
3. Adds two numbers
4. Defines a function

Answer: B — Compares two values for equality and returns a boolean

`==` is the comparison operator; `=` is typically assignment (in C-family languages and Python).

An array (or list) is:

1. Single value
2. Hash table
3. Ordered collection of values, typically indexed (often 0-based) — supports random access by index; size may be fixed or dynamic
4. Object
5. Random data

Answer: C — Ordered collection of values, typically indexed (often 0-based) — supports random access by index; size may be fixed or dynamic

Arrays/lists: most fundamental data structure. Indexed access O(1). Memory: contiguous (array) vs. linked (linked list). Java/C++: fixed-size arrays + dynamic ArrayLists. Python: dynamic list. Off-by-one errors common ('first index is 0').

Which is an example of a high-level programming language?

1. Assembly
2. Machine code
3. Python
4. Binary

Answer: C — Python

Python is high-level (abstract, human-readable). Assembly and machine/binary code are low-level, closer to hardware.

HTTP is:

1. A transport protocol
2. An application-layer protocol for the World Wide Web — request/response model; methods (GET, POST, PUT, DELETE), status codes (200 OK, 404 Not Found, 500 Server Error), headers; HTTPS adds TLS encryption
3. An email protocol
4. A networking layer

Answer: B — An application-layer protocol for the World Wide Web — request/response model; methods (GET, POST, PUT, DELETE), status codes (200 OK, 404 Not Found, 500 Server Error), headers; HTTPS adds TLS encryption

B) Defining role. A/C/D) Each is incorrect.

What does HTML stand for?

1. HyperText Markup Language
2. High-Tech Modern Language
3. Hyperlink and Text Management Layer
4. Home Tool Markup Language

Answer: A — HyperText Markup Language

HTML is the standard markup language for creating web pages.

Which Git command saves staged changes to the local repository's history?

1. git push
2. git commit
3. git clone
4. git pull

Answer: B — git commit

B) Commit records staged changes locally. A) Sends commits to a remote. C) Copies a remote repo. D) Fetches and merges from a remote.

Open-source software is best characterized by:

1. Being free of all bugs
2. Source code available for anyone to view, modify, and distribute, typically under a license like MIT, GPL, or Apache
3. Being illegal to sell
4. Being owned by the U.S. government

Answer: B — Source code available for anyone to view, modify, and distribute, typically under a license like MIT, GPL, or Apache

Open-source means freely accessible source code with permissive (e.g., MIT) or copyleft (e.g., GPL) licensing — it can still be sold or supported commercially.

Which of the following best defines an algorithm?

1. A programming language
2. A finite, well-defined sequence of steps that solves a problem or completes a task
3. A hardware component
4. A type of computer virus

Answer: B — A finite, well-defined sequence of steps that solves a problem or completes a task

An algorithm is a step-by-step procedure with a defined termination — the foundation of all computation.

Flowchart?

Visual representation of algorithm. Boxes + arrows.

HTML?

HyperText Markup Language. Structure of web pages.

What is the internet?

Global network of interconnected networks. Uses TCP/IP protocol suite.

What is computer science?

Study of computation, automation, information. Includes programming, but broader.

Queue (FIFO)?

First In First Out. Like waiting in line.

Common Git commands?

init, clone, add, commit, push, pull, branch, merge.