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55 lines
1.6 KiB
JavaScript
55 lines
1.6 KiB
JavaScript
(function (exports) {
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'use strict';
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var combinations = (function () {
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var res = [];
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function combinations(arr, k, start, idx, current) {
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if (idx === k) {
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res.push(current.slice());
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return;
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}
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for (var i = start; i < arr.length; i += 1) {
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current[idx] = arr[i];
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combinations(arr, k, i + 1, idx + 1, current);
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}
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}
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/**
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* Finds all the combinations of given array.<br><br>
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* A combination is a way of selecting members from a grouping,
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* such that (unlike permutations) the order of selection does not matter.
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* For example given three fruits, say an apple, an orange and a pear,
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* there are three combinations of two that can be drawn from this set:
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* an apple and a pear; an apple and an orange; or a pear and an orange.
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*
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* @example
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*
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* var combinations = require('path-to-algorithms/src/' +
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* 'combinatorics/combinations').combinations;
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* var result = combinations(['apple', 'orange', 'pear'], 2);
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* // [['apple', 'orange'],
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* // ['apple', 'pear'],
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* // ['orange', 'pear']]
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* console.log(result);
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*
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* @module combinatorics/combinations
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* @public
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* @param arr {Array} Set of items.
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* @param k {Number} Size of each combination.
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* @return {Array} Returns all combinations.
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*/
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return function (arr, k) {
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res = [];
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combinations(arr, k, 0, 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.combinations = combinations;
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}((typeof window === 'undefined') ? module.exports : window));
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