javascript-algorithms/src/combinatorics/permutations.js at master · phpsmarter/javascript-algorithms · GitHub

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(function (exports) {

'use strict';

var permutations = (function () {

var res;

function swap(arr, i, j) {

var temp = arr[i];

arr[i] = arr[j];

arr[j] = temp;

}

function permutations(arr, current) {

if (current >= arr.length) {

return res.push(arr.slice());

}

for (var i = current; i < arr.length; i += 1) {

swap(arr, i, current);

permutations(arr, current + 1);

swap(arr, i, current);

}

/**

* Finds all the permutations of given array.<br><br>

* Permutation relates to the act of rearranging, or permuting,

* all the members of a set into some sequence or order.

* For example there are six permutations of the set {1,2,3}, namely:

* (1,2,3), (1,3,2), (2,1,3), (2,3,1), (3,1,2), and (3,2,1).<br><br>

* Complexity: O(N*N!).

* @example

* var permutations = require('path-to-algorithms/src/' +

* 'combinatorics/permutations').permutations;

* var result = permutations(['apple', 'orange', 'pear']);

* // [ [ 'apple', 'orange', 'pear' ],

* // [ 'apple', 'pear', 'orange' ],

* // [ 'orange', 'apple', 'pear' ],

* // [ 'orange', 'pear', 'apple' ],

* // [ 'pear', 'orange', 'apple' ],

* // [ 'pear', 'apple', 'orange' ] ]

* console.log(result);

* @module combinatorics/permutations

* @public

* @param {Array} arr Array to find the permutations of.

* @returns {Array} Array containing all the permutations.

return function (arr) {

res = [];

permutations(arr, 0);

var temp = res;

// Free the extra memory

res = null;

return temp;

};

}());

exports.permutations = permutations;

}((typeof window === 'undefined') ? module.exports : window));

javascript-algorithms/src/combinatorics/permutations.js at master · phpsmarter/javascript-algorithms · GitHub

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