interactive-coding-challenges

120+ continually updated, interactive, and test-driven coding challenges, with Anki flashcards.

Challenges focus on algorithms and data structures found in coding interviews.

Each challenge has one or more reference solutions that are:

• Fully functional
• Unit tested
• Easy-to-understand

Challenges will soon provide on-demand incremental hints to help you arrive at the optimal solution.

Notebooks also detail:

• Constraints
• Test cases
• Algorithms
• Big-O time and space complexities

Also included are unit tested reference implementations of various data structures and algorithms.

Challenge Solutions

Anki Flashcards: Coding and Design

The provided Anki flashcard deck uses spaced repetition to help you retain key concepts.

• Coding deck

Great for use while on-the-go.

Design Resource: The System Design Primer

Looking for resources to help you prep for the System Design and Object-Oriented Design interviews?

Check out the sister repo The System Design Primer, which contains additional Anki decks:

• System design deck
• System design exercises deck
• Object oriented design exercises deck

Notebook Structure

Each challenge has two notebooks, a challenge notebook with unit tests for you to solve and a solution notebook for reference.

Problem Statement

• States the problem to solve.

Constraints

• Describes any constraints or assumptions.

Test Cases

• Describes the general and edge test cases that will be evaluated in the unit test.

Algorithm

• [Challenge Notebook] Empty, refer to the solution notebook algorithm section if you need a hint.
• [Solution Notebook] One or more algorithm solution discussions, with Big-O time and space complexities.

Hints

• [Challenge Notebook] Provides on-demand incremental hints to help you arrive at the optimal solution. Coming soon!

Code (Challenge: Implement Me!)

• [Challenge Notebook] Skeleton code for you to implement.
• [Solution Notebook] One or more reference solutions.

Unit Test

• [Challenge Notebook] Unit test for your code. Expected to fail until you solve the challenge.
• [Solution Notebook] Unit test for the reference solution(s).

Index

Challenges Categories

Format: Challenge Category - Number of Challenges

• Arrays and Strings - 10
• Linked Lists - 8
• Stacks and Queues - 8
• Graphs and Trees - 21
• Sorting - 10
• Recursion and Dynamic Programming - 17
• Mathematics and Probability - 6
• Bit Manipulation - 8
• Online Judges - 16
• System Design - 8
• Object Oriented Design - 8

Total number of challenges: 120

Reference Implementations: Data Structures

Unit tested, fully functional implementations of the following data structures:

• Linked List
• Stack
• Queue
• Binary Search Tree
• Graph
• Min Heap
• Trie
• Priority Queue
• Hash Map

Reference Implementations: Algorithms

Unit tested, fully functional implementations of the following algorithms:

• Selection Sort
• Insertion Sort
• Quick Sort
• Merge Sort
• Radix Sort
• Topological Sort
• Tree Depth-First Search (Pre-, In-, Post-Order)
• Tree Breadth-First Search
• Graph Depth-First Search
• Graph Breadth-First Search
• Dijkstra's Shortest Path
• Unweighted Graph Shortest Path
• Knapsack 0/1
• Knapsack Unbounded
• Sieve of Eratosthenes

Reference Implementations: TODO

• A*
• Bellman-Ford
• Bloom Filter
• Convex Hull
• Fisher-Yates Shuffle
• Kruskal's
• Max Flow
• Prim's
• Rabin-Karp
• Traveling Salesman
• Union Find
• Contribute

Installing and Running Challenges

• Repo Structure
• Notebook Installation
• Running Challenges

Misc

• Contributing
• Credits
• Contact Info
• License

Challenges

Image Credits

Arrays and Strings

Challenge	Static Notebook
Determine if a string contains unique characters	Challenge │ Solution
Determine if a string is a permutation of another	Challenge │ Solution
Determine if a string is a rotation of another	Challenge │ Solution
Compress a string	Challenge │ Solution
Reverse characters in a string	Challenge │ Solution
Given two strings, find the single different char	Challenge │ Solution
Find two indices that sum to a specific value	Challenge │ Solution
Implement a hash table	Challenge │ Solution
Implement fizz buzz	[Challenge](http://nbviewer.ipython.org/github/donnemartin/interactive-coding-challenges/blob/master/arrays_strings/fizz_buzz/fizz_buzz_challenge.ipyn