Percom

Combination and Permutation library

Usage

$ npm i percom

1. Combinatioins (組み合わせ)

  const percom = require("percom");

  percom.com(array,num); 
  //array => Target array (対象の配列)
  //num => Number to combine as combinations (組み合わせの数)

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 the number of combination elements (組み合わせの数を数える)

  percom.countCom(n, r);
  //n => Number of elements : int (要素数)
  //r => Number to choose : int (選ぶ要素の数)

Example

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

2. Permutations (順列)

  percom.per(array,num);
  //array => Target array (対象の配列)
  //num => Number to combine as permutations (一つ一つの順列の要素数)

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 the number of permutation elements (順列の数を数える)

  percom.countPer(n, r);
  //n => Number of elements : int (要素数)
  //r => Number to choose : int (選ぶ要素の数)

Example

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

Test Coverage

Both uncovered lines are returning of recursive function

License

percom is under MIT license

Development

yarn install

// before create PR
yarn mocha

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

Developer

Kota Yatagai (https://twitter.com/kota_yata)