@math-x-ts/generix/lib/esm/Combination.js

This library tasks is to generate combinations and permutations

/**
 * Class to generate combinations with & without repetition.
 */
var Combination = /** @class */ (function () {
    function Combination() {
    }
    /**
     * The concrete implementation of the combination without repetition algorithm.
     *
     * @template S - The type of the elements in the input array.
     * @param {Array<S>} elements - The input array containing the elements to generate combination for.
     * @param {number} startIndex - The starting index for.
     * @param {Array<Array<S>>} currentCombination - The accumulated combination during the recursion.
     * @param {number} n - The minimum length of the generated combination (inclusive).
     * @param {number} m - The maximum length of the generated combination (inclusive).
     *
     * @returns {Array<Array<S>>} - An array of arrays, where each inner array is a combination of the input elements.
     */
    Combination.generateWithoutRepetition = function (elements, startIndex, currentCombination, n, m) {
        var result = [];
        if (currentCombination.length >= n && currentCombination.length <= m) {
            result.push(currentCombination.slice());
        }
        if (currentCombination.length >= m) {
            return result;
        }
        for (var i = startIndex; i < elements.length; i++) {
            currentCombination.push(elements[i]);
            var combinations = Combination.generateWithoutRepetition(elements, i + 1, currentCombination, n, m);
            result.push.apply(result, combinations);
            currentCombination.pop();
        }
        return result;
    };
    /**
     * Generates all possible combinations without repetition of a given array of elements, with the option to specify
     * the minimum (n) and maximum (m) lengths of the generated permutations.
     *
     * @template S - The type of the elements in the input array.
     * @param {Array<S>} elements - The input array containing the elements to generate combination for.
     * @param {number} [n=elements.length] - The minimum length of the generated combination (inclusive).
     * @param {number} [m=n] - The maximum length of the generated combination (inclusive).
     * @returns {Array<Array<S>>} - An array of arrays, where each inner array is a combination of the input elements.
     */
    Combination.withoutRepetition = function (elements, n, m) {
        if (n === void 0) { n = elements.length; }
        if (m === void 0) { m = n; }
        var result = Combination.generateWithoutRepetition(elements, 0, [], n, m);
        return result.sort(function (a, b) { return a.length - b.length; });
    };
    /**
     * The concrete implementation of the combination with repetition algorithm.
     *
     * @template S - The type of the elements in the input array.
     * @param {Array<S>} elements - The input array containing the elements to generate combination for.
     * @param {Array<number>} currentIndexes - The combination indexes accumulated during recursion.
     * @param {number} n - The minimum length of the generated combination (inclusive).
     * @param {number} index - The current index, initially this should be 0.
     * @param {number} startIndex - The starting index from where the combination should begin.
     *
     * @returns {Array<Array<S>>} - An array of arrays, where each inner array is a combination of the input elements.
     */
    Combination.generateWithRepetition = function (elements, currentIndexes, n, index, startIndex) {
        var result = [];
        if (index === n) {
            var combo = [];
            for (var i = 0; i < n; i++) {
                combo.push(elements[currentIndexes[i]]);
            }
            return [combo];
        }
        for (var i = startIndex; i < elements.length; i++) {
            currentIndexes[index] = i;
            result.push.apply(result, Combination.generateWithRepetition(elements, currentIndexes, n, index + 1, i));
        }
        return result;
    };
    /**
     * Generates all possible combinations with repetition of a given array of elements, with the option to specify
     * the minimum (n) and maximum (m) lengths of the generated permutations.
     *
     * @template S - The type of the elements in the input array.
     * @param {Array<S>} elements - The input array containing the elements to generate combination for.
     * @param {number} [n=elements.length] - The minimum length of the generated combination (inclusive).
     * @param {number} [m=n] - The maximum length of the generated combination (inclusive).
     * @returns {Array<Array<S>>} - An array of arrays, where each inner array is a combination of the input elements.
     */
    Combination.withRepetition = function (elements, n, m) {
        if (n === void 0) { n = elements.length; }
        if (m === void 0) { m = n; }
        var result = [];
        for (var i = n; i <= m; i++) {
            var currentIndexes = [];
            for (var j = 0; j < i; j++) {
                currentIndexes.push(0);
            }
            result.push.apply(result, Combination.generateWithRepetition(elements, currentIndexes, i, 0, 0));
        }
        return result;
    };
    return Combination;
}());
export default Combination;
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