75 lines
2.2 KiB
JavaScript
75 lines
2.2 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.createCombinations = void 0;
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var _factory = require("../../utils/factory.js");
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var _combinations = require("../../plain/number/combinations.js");
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const name = 'combinations';
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const dependencies = ['typed'];
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const createCombinations = exports.createCombinations = /* #__PURE__ */(0, _factory.factory)(name, dependencies, _ref => {
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let {
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typed
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} = _ref;
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/**
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* Compute the number of ways of picking `k` unordered outcomes from `n`
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* possibilities.
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*
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* Combinations only takes integer arguments.
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* The following condition must be enforced: k <= n.
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*
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* Syntax:
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*
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* math.combinations(n, k)
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*
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* Examples:
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*
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* math.combinations(7, 5) // returns 21
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*
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* See also:
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*
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* combinationsWithRep, permutations, factorial
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*
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* @param {number | BigNumber} n Total number of objects in the set
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* @param {number | BigNumber} k Number of objects in the subset
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* @return {number | BigNumber} Number of possible combinations.
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*/
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return typed(name, {
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'number, number': _combinations.combinationsNumber,
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'BigNumber, BigNumber': function (n, k) {
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const BigNumber = n.constructor;
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let result, i;
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const nMinusk = n.minus(k);
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const one = new BigNumber(1);
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if (!isPositiveInteger(n) || !isPositiveInteger(k)) {
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throw new TypeError('Positive integer value expected in function combinations');
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}
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if (k.gt(n)) {
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throw new TypeError('k must be less than n in function combinations');
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}
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result = one;
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if (k.lt(nMinusk)) {
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for (i = one; i.lte(nMinusk); i = i.plus(one)) {
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result = result.times(k.plus(i)).dividedBy(i);
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}
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} else {
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for (i = one; i.lte(k); i = i.plus(one)) {
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result = result.times(nMinusk.plus(i)).dividedBy(i);
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}
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}
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return result;
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}
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// TODO: implement support for collection in combinations
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});
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});
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/**
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* Test whether BigNumber n is a positive integer
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* @param {BigNumber} n
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* @returns {boolean} isPositiveInteger
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*/
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function isPositiveInteger(n) {
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return n.isInteger() && n.gte(0);
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} |