Percom

Utility for listing and counting combinations and permutations.

Install

$ npm i percom

Usage

1. List all combinations

import percom from "percom";

percom.com(array, r);
// array: source array
// r: size of each combination

Example

const array = ["A", "B", "C"];

const result1 = percom.com(array, 2);
// result1 = [["A", "B"], ["A", "C"], ["B", "C"]]

const result2 = percom.com(array, 1);
// result2 = [["A"], ["B"], ["C"]]

Count combinations

percom.countCom(n, r);
// n: number of elements
// r: size of each combination

Example

percom.countCom(8, 3); // => 56

2. List all permutations

percom.per(array, r);
// array: source array
// r: size of each permutation

Example

const array = ["A", "B", "C"];

const result1 = percom.per(array, 2);
// result1 = [["A", "B"], ["A", "C"], ["B", "A"], ["B", "C"], ["C", "A"], ["C", "B"]]

const result2 = percom.per(array, 1);
// result2 = [["A"], ["B"], ["C"]]

Count permutations

percom.countPer(n, r);
// n: number of elements
// r: size of each permutation

Example

percom.countPer(8, 3); // => 336

License

percom is available under the MIT License.

Development

yarn install

// before creating a PR
yarn mocha

Since lint-staged and husky are set up, your code will be formatted before commit.

Developer

Kota Yatagai (https://kota_yata.com)