Free Computer Science Basics Flashcards

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Algorithm

A step-by-step procedure for solving a problem or accomplishing a task

Variable

A named storage location in memory that holds a value; can change during program execution

Array

An ordered collection of elements stored in contiguous memory; accessed by index; fixed size

Loop

Code that repeats execution; types: for loop (known iterations), while loop (condition-based)

Function

A reusable block of code that performs a specific task; takes inputs (parameters), returns output

Conditional Statement

Code that executes based on a condition; if/else/else if; controls program flow

Boolean

A data type with only two values: true or false; used in conditions and logic

String

A sequence of characters (text); immutable in many languages; enclosed in quotes

Integer

A whole number data type; no decimal point; positive, negative, or zero

Binary

Base-2 number system using 0s and 1s; how computers store all data

Big O Notation

Describes algorithm efficiency; O(1) constant, O(n) linear, O(n²) quadratic, O(log n) logarithmic

Stack

LIFO data structure (Last In, First Out); push adds, pop removes; like a stack of plates

Queue

FIFO data structure (First In, First Out); enqueue adds, dequeue removes; like a line of people

Linked List

Data structure where each element points to the next; dynamic size; no contiguous memory required

Hash Table

Key-value data structure; O(1) average lookup; handles collisions; used in dictionaries/maps

Binary Tree

Tree where each node has at most 2 children; binary search tree: left < parent < right

Recursion

A function that calls itself; needs a base case to stop; used for trees, fractals, divide-and-conquer

Sorting Algorithms

Bubble sort O(n²), merge sort O(n log n), quick sort O(n log n) avg; organize data in order

Binary Search

Efficient search on sorted data; divides in half each step; O(log n) time complexity

Object-Oriented Programming

Programming paradigm using objects with properties and methods; classes, inheritance, encapsulation, polymorphism

Class

A blueprint for creating objects; defines properties (attributes) and methods (behaviors)

Inheritance

A class can inherit properties and methods from a parent class; promotes code reuse

API

Application Programming Interface; defines how software components interact; request/response pattern

HTTP Methods

GET (retrieve), POST (create), PUT (update), DELETE (remove); used in web APIs

Database

Organized collection of data; SQL (relational tables) vs NoSQL (documents, key-value, graph)

Git

Version control system; tracks code changes; commands: commit, push, pull, branch, merge

Compiler vs Interpreter

Compiler: translates entire program before running; Interpreter: translates line by line during execution

Bug

An error in code; syntax error (won't compile), logic error (wrong result), runtime error (crashes)

Testing

Verifying code works correctly; unit tests (individual functions), integration tests (components together)

Time Complexity

How running time grows with input size; constant O(1) < logarithmic O(log n) < linear O(n) < quadratic O(n²)

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