64 lines
1.8 KiB
JavaScript
64 lines
1.8 KiB
JavaScript
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(function (exports) {
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'use strict';
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var permutations = (function () {
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var res;
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function swap(arr, i, j) {
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var temp = arr[i];
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arr[i] = arr[j];
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arr[j] = temp;
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}
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function permutations(arr, current) {
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if (current >= arr.length) {
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return res.push(arr.slice());
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}
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for (var i = current; i < arr.length; i += 1) {
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swap(arr, i, current);
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permutations(arr, current + 1);
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swap(arr, i, current);
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}
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}
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/**
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* Finds all the permutations of given array.<br><br>
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* Permutation relates to the act of rearranging, or permuting,
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* all the members of a set into some sequence or order.
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* For example there are six permutations of the set {1,2,3}, namely:
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* (1,2,3), (1,3,2), (2,1,3), (2,3,1), (3,1,2), and (3,2,1).<br><br>
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* Complexity: O(N*N!).
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*
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* @example
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*
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* var permutations = require('path-to-algorithms/src/' +
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* 'combinatorics/permutations').permutations;
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* var result = permutations(['apple', 'orange', 'pear']);
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*
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* // [ [ 'apple', 'orange', 'pear' ],
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* // [ 'apple', 'pear', 'orange' ],
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* // [ 'orange', 'apple', 'pear' ],
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* // [ 'orange', 'pear', 'apple' ],
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* // [ 'pear', 'orange', 'apple' ],
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* // [ 'pear', 'apple', 'orange' ] ]
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* console.log(result);
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*
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* @module combinatorics/permutations
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* @public
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* @param {Array} arr Array to find the permutations of.
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* @returns {Array} Array containing all the permutations.
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*/
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return function (arr) {
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res = [];
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permutations(arr, 0);
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var temp = res;
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// Free the extra memory
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res = null;
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return temp;
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};
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}());
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exports.permutations = permutations;
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}((typeof window === 'undefined') ? module.exports : window));
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