Rust Programming Guide

The 80/20 Guide: Master the 20% of Rust that solves 80% of problems

This guide is designed for developers who want to learn Rust quickly, retain knowledge effectively, and prepare for coding interviews. It follows the 80/20 principle—focusing on the essential concepts that give you maximum leverage.

Prerequisites

Rust 1.85+ minimum (Rust 2024 Edition)
Rust 1.96+ recommended (current stable as of mid-2026)
rustup and cargo installed
Basic programming knowledge

Why Rust for Interviews?

Advantage	Details
Memory Safety	No garbage collector, no null pointer exceptions, no data races—guaranteed at compile time
Performance	Zero-cost abstractions, compiled to native code, competitive with C/C++
Pattern Matching	Exhaustive `match` expressions make complex logic clear and bug-free
Error Handling	`Result` and `Option` types force explicit handling—no forgotten edge cases
Iterators	Powerful functional-style chains that compile to efficient loops
Type System	Strong generics with trait bounds catch bugs before runtime

Learning Path (5-Week Plan)

Week 1: Foundations
├── Day 1-2: Syntax & Types (01-syntax-quick-reference.md)
├── Day 3-4: Ownership & Borrowing (02-ownership-borrowing.md)
└── Day 5-7: Practice easy problems in Rust

Week 2: Data Structures
├── Day 1-2: Collections & Custom Types (03-data-structures.md)
├── Day 3-4: Interview Patterns Part 1 (04-interview-patterns.md)
└── Day 5-7: Practice medium problems

Week 3: Patterns & Idioms
├── Day 1-2: Interview Patterns Part 2 (04-interview-patterns.md)
├── Day 3-4: Rust Idioms & Error Handling (05-idioms-best-practices.md)
└── Day 5-7: Practice hard problems

Week 4: Advanced & Interview Simulation
├── Day 1-2: Concurrency & Parallelism (06-concurrency.md)
├── Day 3: Tooling & Workflow (07-tooling-workflow.md)
├── Day 4-5: Timed problem solving
└── Day 6-7: Mock interviews

Week 5: Design Patterns & Interview Mastery
├── Day 1: SOLID Principles (08-solid-principles.md)
├── Day 2-3: Design Patterns (09, 10, 11-design-patterns-*.md)
├── Day 4: Anti-Patterns & Best Practices (12-anti-patterns-best-practices.md)
├── Day 5-6: Interview Trap Questions (13-interview-trap-questions.md)
└── Day 7: Final review and mock interviews

Week 6: Advanced Topics & Testing
├── Day 1-2: Standard Library Essentials (17-std-library-essentials.md)
├── Day 3-4: Test-Driven Development (18-test-driven-development.md)
├── Day 5: Macros (14-macros.md)
└── Day 6-7: Unsafe Rust & FFI, WebAssembly (15, 16)

Week 7: Specialization
├── Day 1-2: Deep dive into areas of interest
├── Day 3-4: Build a small project using TDD
└── Day 5-7: Final review and mock interviews

Guide Contents

File	Focus	Time
01-syntax-quick-reference.md	Essential syntax, types, pattern matching	45 min
02-ownership-borrowing.md	Ownership, borrowing, lifetimes—Rust's core	90 min
03-data-structures.md	Vec, HashMap, BinaryHeap, custom types	60 min
04-interview-patterns.md	17 algorithm patterns in idiomatic Rust	120 min
05-idioms-best-practices.md	Error handling, traits, iterators, testing	45 min
06-concurrency.md	Threads, channels, async, Rayon parallelism	60 min
07-tooling-workflow.md	Cargo, Clippy, rustfmt, CI/CD	30 min
08-solid-principles.md	SOLID principles adapted for Rust	45 min
09-design-patterns-creational.md	Builder, Factory, Singleton, Prototype	45 min
10-design-patterns-structural.md	Adapter, Decorator, Facade, Composite, Proxy	45 min
11-design-patterns-behavioral.md	Strategy, Observer, State, Command, Iterator	60 min
12-anti-patterns-best-practices.md	Common pitfalls and idiomatic practices	45 min
13-interview-trap-questions.md	Tricky interview questions with deep explanations	75 min
14-macros.md	Declarative and procedural macros, metaprogramming	60 min
15-unsafe-ffi.md	Unsafe Rust, FFI, interfacing with C	75 min
16-webassembly.md	WebAssembly, WASI, Component Model	45 min
17-std-library-essentials.md	Collections, iterators, I/O, sync, formatting	90 min
18-test-driven-development.md	TDD, QA mindset, proptest, mocking, coverage	90 min

The 80/20 of Rust

20% of Concepts That Matter Most

Ownership — Every value has exactly one owner; memory freed when owner goes out of scope
Borrowing — References (&T, &mut T) allow access without ownership transfer
Vec — The dynamic array, your workhorse for algorithms
HashMap<K, V> — O(1) lookups, complement searching, counting
Pattern Matching — match, if let, destructuring for clean logic
Result & Option — Error and null handling without exceptions
Iterators — map, filter, fold, collect for functional transformations
Traits — Shared behavior, like interfaces but more powerful
Enums — Algebraic data types for state machines and variants
Lifetimes — 'a annotations when the compiler needs help with references

Essential Standard Library

use std::collections::{HashMap, HashSet, VecDeque, BinaryHeap, BTreeMap};
use std::cmp::{min, max, Ordering, Reverse};
use std::iter::FromIterator;

// Creating collections
let v: Vec<i32> = vec![1, 2, 3];
let map: HashMap<&str, i32> = HashMap::new();
let set: HashSet<i32> = HashSet::new();

// Useful methods
v.len()                    // Length
v.is_empty()               // Check empty
v.iter()                   // Iterator over &T
v.into_iter()              // Iterator over T (consumes)
v.iter_mut()               // Iterator over &mut T

// Iterator chains
nums.iter()
    .filter(|&x| x % 2 == 0)
    .map(|x| x * 2)
    .collect::<Vec<_>>()

Quick Start: Your First Algorithm in Rust

Two Sum Implementation

use std::collections::HashMap;

fn two_sum(nums: &[i32], target: i32) -> Option<(usize, usize)> {
    let mut seen: HashMap<i32, usize> = HashMap::new();

    for (i, &num) in nums.iter().enumerate() {
        let complement = target - num;
        if let Some(&j) = seen.get(&complement) {
            return Some((j, i));
        }
        seen.insert(num, i);
    }
    None
}

fn main() {
    let nums = vec![2, 7, 11, 15];
    let target = 9;

    match two_sum(&nums, target) {
        Some((i, j)) => println!("Indices: {}, {}", i, j),
        None => println!("No solution found"),
    }
}

Key Rust concepts demonstrated:

&[i32] — Slice reference (borrows the data)
HashMap::new() — Creating a hash map
.iter().enumerate() — Iterate with indices
if let Some(&j) — Pattern matching with destructuring
Option<(usize, usize)> — Explicit null handling
match expression — Exhaustive pattern matching

Rust vs Other Languages

Feature	Rust	Python	Go	C++
Array declaration	`let nums = vec![1,2,3];`	`nums = [1,2,3]`	`nums := []int{1,2,3}`	`vector<int> nums = {1,2,3};`
Hash map	`HashMap::new()`	`{}`	`make(map[K]V)`	`unordered_map<K,V>`
For loop	`for i in 0..n`	`for i in range(n)`	`for i := 0; i < n; i++`	`for(int i=0; i<n; i++)`
Iteration	`for x in &arr`	`for x in arr`	`for _, x := range arr`	`for(auto& x : arr)`
Null check	`if let Some(x) = opt`	`if x is not None`	`if x != nil`	`if(x != nullptr)`
Error handling	`result?`	`try/except`	`if err != nil`	`try/catch`
Memory	Ownership	GC	GC	Manual/RAII

Interview Tips for Rust

1. Start with the Signature

// Always clarify input/output types first
fn solve(nums: &[i32], target: i32) -> Vec<i32> {
    // Implementation
    vec![]
}

2. Use Idiomatic Rust

// Good: Iterator chains
let sum: i32 = nums.iter().filter(|&&x| x > 0).sum();

// Good: Pattern matching
match result {
    Ok(value) => process(value),
    Err(e) => handle_error(e),
}

// Good: Option chaining
let result = map.get(&key)?.checked_add(1)?;

3. Know Your Complexities

// O(1) - HashMap operations
map.get(&key);
map.insert(key, value);
map.contains_key(&key);

// O(1) amortized - Vec push
vec.push(element);

// O(n) - Vec contains/search
vec.contains(&target);
vec.iter().position(|&x| x == target);

// O(log n) - BinaryHeap, BTreeMap
heap.push(value);
btree.get(&key);

// O(log n) - Binary search (sorted slice)
slice.binary_search(&target);

// O(n log n) - Sorting
vec.sort();
vec.sort_by(|a, b| a.cmp(b));

4. Handle Edge Cases

fn solve(nums: &[i32]) -> i32 {
    // Always check edge cases first
    if nums.is_empty() {
        return 0;
    }
    if nums.len() == 1 {
        return nums[0];
    }
    // Main logic...
    0
}

5. Ownership-Aware Patterns

// When you need to modify while iterating: indices
for i in 0..nums.len() {
    // Can modify nums[i]
}

// When building a result: collect
let result: Vec<_> = nums.iter().map(|x| x * 2).collect();

// When you need ownership: into_iter or clone
let owned: Vec<i32> = borrowed.to_vec();

Practice Problems by Pattern

Start with these problems from the main repository, implementing solutions in Rust:

Foundation (Start Here)

E001 Two Sum — HashMap lookup
E014 Valid Parentheses — Stack with Vec

Two Pointers

E006 Container With Most Water
Practice with sorted slices, palindrome checking

Sliding Window

M002 Longest Substring
Practice with HashMap for tracking characters

Binary Search

Practice with .binary_search() and custom comparators

Dynamic Programming

Practice with 2D vectors (Vec<Vec<i32>>)

Resources

Official Documentation

The Rust Book — Comprehensive official guide
Rust by Example — Learn by annotated examples
Standard Library Docs — API reference

Interactive Learning

Rustlings — Small exercises to learn Rust
Exercism Rust Track — Practice problems with mentorship

Interview Preparation

Rust Cookbook — Common tasks and patterns
Algorithms in Rust — Algorithm implementations

Essential Ecosystem Crates

These are the must-know crates in the Rust ecosystem (2025):

Core Libraries

Category	Crate	Purpose
Async	tokio	Async runtime (industry standard)
Serialization	serde	Serialization framework
JSON	serde_json	JSON parsing/generation
Error (lib)	thiserror	Derive Error for libraries
Error (app)	anyhow	Error handling for apps
Parallelism	rayon	Data parallelism
Logging	tracing	Structured logging

Web & Network

Category	Crate	Purpose
Web Framework	axum	Web framework (Tokio)
HTTP Client	reqwest	HTTP client
gRPC	tonic	gRPC framework

Database & CLI

Category	Crate	Purpose
SQL	sqlx	Async SQL toolkit
CLI	clap	Command-line parsing

Testing

Category	Crate	Purpose
Property Testing	proptest	Property-based testing
Mocking	mockall	Mocking framework
Benchmarking	criterion	Statistical benchmarks

Spaced Repetition Schedule

Use this schedule to retain Rust knowledge:

Day	Review
1	Write Two Sum from memory
3	Implement stack with Vec, explain ownership
7	Write binary search, explain borrowing
14	Implement graph BFS with ownership handling
21	Code a DP solution with 2D Vec
30	Timed mock interview in Rust

The Rust Mindset

"If it compiles, it works."

Rust's strict compiler catches bugs at compile time that would be runtime errors in other languages. Embrace the compiler as your pair programmer:

Read error messages carefully — Rust's errors are famously helpful
Trust the borrow checker — It's protecting you from data races and dangling pointers
Prefer iterators — They're zero-cost abstractions that often compile to the same code as manual loops
Use clippy — cargo clippy catches common mistakes and suggests improvements

Rust is hard to learn but easy to use correctly.
Master ownership, and everything else follows.

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Rust Programming Guide

Prerequisites

Why Rust for Interviews?

Learning Path (5-Week Plan)

Guide Contents

The 80/20 of Rust

20% of Concepts That Matter Most

Essential Standard Library

Quick Start: Your First Algorithm in Rust

Two Sum Implementation

Rust vs Other Languages

Interview Tips for Rust

1. Start with the Signature

2. Use Idiomatic Rust

3. Know Your Complexities

4. Handle Edge Cases

5. Ownership-Aware Patterns

Practice Problems by Pattern

Foundation (Start Here)

Two Pointers

Sliding Window

Binary Search

Dynamic Programming

Resources

Official Documentation

Interactive Learning

Interview Preparation

Essential Ecosystem Crates

Core Libraries

Web & Network

Database & CLI

Testing

Spaced Repetition Schedule

The Rust Mindset

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README.md

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Rust Programming Guide

Prerequisites

Why Rust for Interviews?

Learning Path (5-Week Plan)

Guide Contents

The 80/20 of Rust

20% of Concepts That Matter Most

Essential Standard Library

Quick Start: Your First Algorithm in Rust

Two Sum Implementation

Rust vs Other Languages

Interview Tips for Rust

1. Start with the Signature

2. Use Idiomatic Rust

3. Know Your Complexities

4. Handle Edge Cases

5. Ownership-Aware Patterns

Practice Problems by Pattern

Foundation (Start Here)

Two Pointers

Sliding Window

Binary Search

Dynamic Programming

Resources

Official Documentation

Interactive Learning

Interview Preparation

Essential Ecosystem Crates

Core Libraries

Web & Network

Database & CLI

Testing

Spaced Repetition Schedule

The Rust Mindset