@beenotung/tslib/combination.js

utils library in Typescript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.combinations = void 0;
exports.any_combinations = any_combinations;
exports.n_combinations = n_combinations;
/**
 *  @description combination: order doesn't matter
 *  @description known bug: will have integer overflow when the list is too long
 */
function any_combinations(xs) {
    const xss = [];
    const listLen = xs.length;
    const combinationCount = 1 << listLen;
    for (let i = 1; i < combinationCount; i++) {
        const ys = [];
        for (let j = 0; j < listLen; j++) {
            if (i & (1 << j)) {
                ys.push(xs[j]);
            }
        }
        xss.push(ys);
    }
    return xss;
}
/** @description combination: order doesn't matter */
function n_combinations(n, xs) {
    if (n == 0)
        return [];
    if (n == 1)
        return xs.map(x => [x]);
    return xs.flatMap((x, i) => n_combinations(n - 1, xs.slice(i + 1)).map(xs => [x, ...xs]));
}
/** @deprecated renamed to `any_combinations` */
exports.combinations = any_combinations;