dist-javascript-algorithms-and-data-structures/dist/algorithms/sets/permutations/permutateWithoutRepetitions.js

Algorithms and data-structures implemented on JavaScript

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = permutateWithoutRepetitions;

/**
 * @param {*[]} permutationOptions
 * @return {*[]}
 */
function permutateWithoutRepetitions(permutationOptions) {
  if (permutationOptions.length === 1) {
    return [permutationOptions];
  } // Init permutations array.


  const permutations = []; // Get all permutations for permutationOptions excluding the first element.

  const smallerPermutations = permutateWithoutRepetitions(permutationOptions.slice(1)); // Insert first option into every possible position of every smaller permutation.

  const firstOption = permutationOptions[0];

  for (let permIndex = 0; permIndex < smallerPermutations.length; permIndex += 1) {
    const smallerPermutation = smallerPermutations[permIndex]; // Insert first option into every possible position of smallerPermutation.

    for (let positionIndex = 0; positionIndex <= smallerPermutation.length; positionIndex += 1) {
      const permutationPrefix = smallerPermutation.slice(0, positionIndex);
      const permutationSuffix = smallerPermutation.slice(positionIndex);
      permutations.push(permutationPrefix.concat([firstOption], permutationSuffix));
    }
  }

  return permutations;
}