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Software: explore STEM content (page 17 of 25) · openstem

All fields Software Mathematics Physics Chemistry Biology Engineering Astronomy Environmental Other Software Software groups

Explore STEM Content

Search the community's STEM library — free to study, yours to make your own.

Software

Programming, algorithms and systems on openstem — flashcards, notes, quizzes, sketches and flowcharts shared by the community. Study free, or clone anything into your library.

Content Groups1

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Note~287 words · 1 min

Big-O complexity cheat sheet Big-O notation describes how an algorithm's running time or space grows with input size n, ignoring constant factors and lower-order terms. Common complexity classes (fastest → slowest) Binary search example Bin

Software

Software · L4 · Big-O complexity cheat sheet

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Software · L4 · Big-O complexity cheat sheet

Flowchart14 objects

Software

Software · L1 · Testing: The Red-Green-Refactor Cycle · flowchart

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Software · L1 · Testing: The Red-Green-Refactor Cycle · flowchart

Flowchart18 objects

Software

Software · L5 · The Cryptographic Primitive Hierarchy

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Software · L5 · The Cryptographic Primitive Hierarchy

Collection4 items

01Postgres Features

02PostgreSQL Basics

03Software · L1 · PostgreSQL: Full-Text Search

+1 more

Software

Software · L1 · PostgreSQL

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Software · L1 · PostgreSQL

Flashcards10 cards

What is a software supply-chain attack?1 / 10

Compromising software via its dependencies, build pipeline, or distribution rather than the target's own code — e.g. a poisoned npm package or a tampered build server — so the malicious code reaches users through trusted channels.

Software

Secure SDLC & Supply-Chain Security

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Secure SDLC & Supply-Chain Security

Flashcards9 cards

What is the GIL and what does it mean for CPU-bound vs I/O-bound Python code?1 / 9

The Global Interpreter Lock (GIL) in CPython allows only one thread to execute Python bytecode at a time. CPU-bound threads do NOT run in parallel — use multiprocessing or C extensions. I/O-bound threads DO get effective concurrency because the GIL is released during I/O waits.

Software

Performance & Internals

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Performance & Internals

Collection4 items

01Data Partitioning & Replication at Scale

02Software · L4 · Data Partitioning & Replication at Scale

03Software · L4 · Sharded write path with leader-follower replication

+1 more

Software

Software · L4 · Data Partitioning & Replication

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Software · L4 · Data Partitioning & Replication

Flashcards8 cards

What is the difference between `__str__` and `__repr__`?1 / 8

`__repr__` should return an unambiguous technical string for developers (ideally eval-able). `__str__` returns a human-readable string for end users. `str()` calls `__str__`; if missing, falls back to `__repr__`. Always implement `__repr__` at minimum.

Software

OOP & Classes

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OOP & Classes

Note~81 words · 1 min

From URL to Rendered Page A single 'visit this page' action hides several layered protocol steps, each building on the one before it, before a single byte of HTML is exchanged. With `Connection: keep-alive`, later requests to the same host

Software

Software · L1 · Networking & HTTP: Anatomy of a Web Request

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Software · L1 · Networking & HTTP: Anatomy of a Web Request

Note~418 words · 2 min

SQL essentials SQL (Structured Query Language) is the standard language for relational databases. Understanding its core clauses and their execution order prevents common mistakes. Logical execution order JOIN types Indexes A B-tree index t

Software

Software · L4 · SQL essentials

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Software · L4 · SQL essentials

Flashcards8 cards

What is the core difference between a REST endpoint and a GraphQL endpoint?1 / 8

REST exposes many URLs, each returning a fixed shape of data for one resource. GraphQL exposes a single endpoint backed by a typed schema, and the client's query specifies exactly which fields it wants across related types in one request — fixing both over-fetching (unused fields) and under-fetching (needing several round trips to assemble a view).

Software

GraphQL API Design

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GraphQL API Design

Flashcards10 cards

What is the modern way to configure HTTP security in Spring Security 6?1 / 10

Define a `SecurityFilterChain` bean using the lambda DSL on `HttpSecurity`. As of Spring Security 6 (Spring Boot 3) the component-based `WebSecurityConfigurerAdapter` was removed, so this bean-based approach is the only option.

Software

Spring Security

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Spring Security

Flashcards8 cards

What are the three DFS traversal orders for a binary tree?1 / 8

In-order (Left → Root → Right) — visits BST nodes in sorted order. Pre-order (Root → Left → Right) — useful for serialization/copy. Post-order (Left → Right → Root) — useful for deletion and evaluating expression trees.

Software

Trees & BST

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Trees & BST

Flashcards10 cards

Why does the 'testing trophy' reweight the pyramid toward integration tests, and what assumption changes?1 / 10

The pyramid assumes unit tests are the cheapest path to confidence; the trophy assumes wiring and boundary bugs dominate, so integration tests (real collaborators, mocked edges) buy the most confidence-per-cost. It widens the middle layer and adds static analysis/types as the base, treating heavily-mocked unit tests as low-value.

Software

Test Architecture & Test Doubles

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Test Architecture & Test Doubles

Flashcards10 cards

What is Flutter's core layout rule in one sentence?1 / 10

Constraints go down, sizes go up, and the parent sets the position. A widget receives constraints from its parent, chooses its own size within them, and the parent then positions it.

Software

Layout & Constraints

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Layout & Constraints

Flowchart5 objects

Software

Software · L2 · Java: Concurrency Basics · flowchart

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Software · L2 · Java: Concurrency Basics · flowchart

Flashcards10 cards

What is the God Object anti-pattern?1 / 10

A single class that knows or does too much, centralizing responsibilities and violating the Single Responsibility Principle, making it hard to maintain.

Software

Anti-patterns & Refactoring

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Anti-patterns & Refactoring

Flowchart13 objects

Software

Software · L1 · TypeScript: Handling Optional and Nullish Values · flowchart

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Software · L1 · TypeScript: Handling Optional and Nullish Values · flowchart

Flowchart11 objects

Software

Software · L2 · Python: classmethod, staticmethod, or Instance Method? · flowchart

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Software · L2 · Python: classmethod, staticmethod, or Instance Method? · flowchart

Flashcards10 cards

What characterizes the actor model?1 / 10

Independent actors hold private state and communicate only by asynchronous message passing, so there is no shared mutable memory to guard with locks.

Software

Concurrency Models

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Concurrency Models

Flashcards10 cards

What is an IAM policy?1 / 10

An IAM policy is a JSON document that defines permissions by allowing or denying actions on specified resources under given conditions.

Software

Security & IAM

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Security & IAM

Quiz5 questions

A function only needs to read a Vec<i32>, not own or mutate it. What should its parameter type be?

AVec<i32> (take ownership)B&Vec<i32> (an immutable borrow)C&mut Vec<i32> (a mutable borrow)DVec<i32>.clone()

Software

Software · L1 · Rust: Move, Borrow, or Clone?

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Software · L1 · Rust: Move, Borrow, or Clone?

Collection6 items

01Null Safety

02Async & Futures

03Collections & Generics

+3 more

Software

Software · L2 · Dart

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Software · L2 · Dart

Quiz5 questions

What does to_tsvector() do?

AConverts text into normalized, stemmed lexemesBDeletes a text columnCConverts text into JSONBDEncrypts a text value

Software

Software · L1 · PostgreSQL: Full-Text Search

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Software · L1 · PostgreSQL: Full-Text Search

Flashcards9 cards

What is the key constraint of a React Server Component?1 / 9

It runs only on the server, never ships its code to the client, and cannot use state or effects like useState/useEffect or browser-only APIs. Server Components were stabilized in React 19.

Software

Server Components & Suspense

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Server Components & Suspense

Note~156 words · 1 min

Narrowing Before You Use a Value Once a value's type includes `null` or `undefined`, TypeScript won't let you use it until you've ruled those out. The two most common tools for that are the nullish coalescing operator `??` (supply a default

Software

Software · L1 · TypeScript: Handling Optional and Nullish Values

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Software · L1 · TypeScript: Handling Optional and Nullish Values

Flashcards10 cards

What is the GCP equivalent of AWS EC2 and S3?1 / 10

Compute Engine = virtual machines (≈ EC2). Cloud Storage = object storage in buckets (≈ S3). Cloud Functions = serverless functions (≈ Lambda). GKE = managed Kubernetes (≈ EKS). The cloud primitives map closely across providers.

Software

Core Services

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Core Services

Note~192 words · 1 min

A Class Is a Blueprint A class defines the shape of an object: its fields (state) and methods (behavior). No memory is allocated just by writing a class — an object only exists once you construct one with `new`. Many objects can be built fr

Software

Software · L1 · Java: Classes & Objects

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Software · L1 · Java: Classes & Objects

Flashcards10 cards

What is MVCC in PostgreSQL?1 / 10

Multi-Version Concurrency Control: readers never block writers and writers never block readers, because each transaction sees a consistent snapshot. Updates create new row versions rather than locking; old versions are cleaned up by VACUUM.

Software

Postgres Features

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Postgres Features

Flowchart21 objects

Software

Software · L3 · Choosing an HTTP Method and Status Code

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Software · L3 · Choosing an HTTP Method and Status Code

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