Web Analytics

javascript-algorithms

⭐ 0 stars English by trekhleb

JavaScript Algorithms and Data Structures

🇺🇦 UKRAINE IS BEING ATTACKED BY RUSSIAN ARMY. CIVILIANS ARE GETTING KILLED. RESIDENTIAL AREAS ARE GETTING BOMBED.
- Help Ukraine via:
- Serhiy Prytula Charity Foundation
- Come Back Alive Charity Foundation
- National Bank of Ukraine
- More info on war.ukraine.ua and MFA of Ukraine


CI codecov repo size

This repository contains JavaScript based examples of many popular algorithms and data structures.

Each algorithm and data structure has its own separate README with related explanations and links for further reading (including ones to YouTube videos).

_Read this in other languages:_ _简体中文_, _繁體中文_, _한국어_, _日本語_, _Polski_, _Français_, _Español_, _Português_, _Русский_, _Türkçe_, _Italiano_, _Bahasa Indonesia_, _Українська_, _Arabic_, _Tiếng Việt_, _Deutsch_, _Uzbek_, _עברית_

*☝ Note that this project is meant to be used for learning and researching purposes only, and it is not meant to be used for production.*

Data Structures

A data structure is a particular way of organizing and storing data in a computer so that it can be accessed and modified efficiently. More precisely, a data structure is a collection of data values, the relationships among them, and the functions or operations that can be applied to the data.

Remember that each data structure has its own trade-offs. And you need to pay more attention to why you're choosing a certain data structure than to how to implement it.

B - Beginner, A - Advanced

Algorithms

An algorithm is an unambiguous specification of how to solve a class of problems. It is a set of rules that precisely define a sequence of operations.

B - Beginner, A - Advanced

Algorithms by Topic

Algorithms by Paradigm

An algorithmic paradigm is a generic method or approach which underlies the design of a class of algorithms. It is an abstraction higher than the notion of an algorithm, just as an algorithm is an abstraction higher than a computer program.

if it satisfies all conditions and only then continue generating subsequent solutions. Otherwise, backtrack and go on a different path to finding a solution. Normally the DFS traversal of state-space is being used. search, and use the cost of the lowest-cost solution found so far as a lower bound on the cost of a least-cost solution to the problem in order to discard partial solutions with costs larger than the lowest-cost solution found so far. Normally, BFS traversal in combination with DFS traversal of state-space tree is being used.

How to use this repository

Install all dependencies

npm install

Run ESLint

You may want to run it to check code quality.

npm run lint

Run all tests

npm test

Run tests by name

npm test -- 'LinkedList'

Troubleshooting

If linting or testing is failing, try to delete the node_modules folder and re-install npm packages:

rm -rf ./node_modules
npm i

Also, make sure that you're using the correct Node version (>=16). If you're using nvm for Node version management you may run nvm use from the root folder of the project and the correct version will be picked up.

Playground

You may play with data-structures and algorithms in ./src/playground/playground.js file and write tests for it in ./src/playground/__test__/playground.test.js.

Then just, simply run the following command to test if your playground code works as expected:

npm test -- 'playground'

Useful Information

References

Big O Notation

Big O notation is used to classify algorithms according to how their running time or space requirements grow as the input size grows. On the chart below, you may find the most common orders of growth of algorithms specified in Big O notation.

Big O graphs

Source: Big O Cheat Sheet.

Below is the list of some of the most used Big O notations and their performance comparisons against different sizes of the input data.

| Big O Notation | Type | Computations for 10 elements | Computations for 100 elements | Computations for 1000 elements | | -------------- | ----------- | ---------------------------- | ----------------------------- | ------------------------------- | | O(1) | Constant | 1 | 1 | 1 | | O(log N) | Logarithmic | 3 | 6 | 9 | | O(N) | Linear | 10 | 100 | 1000 | | O(N log N) | n log(n) | 30 | 600 | 9000 | | O(N^2) | Quadratic | 100 | 10000 | 1000000 | | O(2^N) | Exponential | 1024 | 1.26e+29 | 1.07e+301 | | O(N!) | Factorial | 3628800 | 9.3e+157 | 4.02e+2567 |

Data Structure Operations Complexity

| Data Structure | Access | Search | Insertion | Deletion | Comments | | ----------------------- | :-------: | :-------: | :-------: | :-------: | :-------- | | Array | 1 | n | n | n | | | Stack | n | n | 1 | 1 | | | Queue | n | n | 1 | 1 | | | Linked List | n | n | 1 | n | | | Hash Table | - | n | n | n | In case of perfect hash function costs would be O(1) | | Binary Search Tree | n | n | n | n | In case of balanced tree costs would be O(log(n)) | | B-Tree | log(n) | log(n) | log(n) | log(n) | | | Red-Black Tree | log(n) | log(n) | log(n) | log(n) | | | AVL Tree | log(n) | log(n) | log(n) | log(n) | | | Bloom Filter | - | 1 | 1 | - | False positives are possible while searching |

Array Sorting Algorithms Complexity

| Name | Best | Average | Worst | Memory | Stable | Comments | | --------------------- | :-------------: | :-----------------: | :-----------------: | :-------: | :-------: | :-------- | | Bubble sort | n | n2 | n2 | 1 | Yes | | | Insertion sort | n | n2 | n2 | 1 | Yes | | | Selection sort | n2 | n2 | n2 | 1 | No | | | Heap sort | n log(n) | n log(n) | n log(n) | 1 | No | | | Merge sort | n log(n) | n log(n) | n log(n) | n | Yes | | | Quick sort | n log(n) | n log(n) | n2 | log(n) | No | Quicksort is usually done in-place with O(log(n)) stack space | | Shell sort | n log(n) | depends on gap sequence | n (log(n))2 | 1 | No | | | Counting sort | n + r | n + r | n + r | n + r | Yes | r - biggest number in array | | Radix sort | n k | n k | n * k | n + k | Yes | k - length of longest key |

Project Backers

You may support this project via ❤️️ GitHub or ❤️️ Patreon.

Folks who are backing this project ∑ = 1

Author

@trekhleb

A few more projects and articles about JavaScript and algorithms on trekhleb.dev

--- Powered By OpenAiTx ---