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permutateWithRepetitions.js
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permutateWithRepetitions.js
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/**
* @param {*[]} permutationOptions
* @param {number} permutationLength
* @return {*[]}
*/
export default function permutateWithRepetitions(
permutationOptions,
permutationLength = permutationOptions.length,
) {
if (permutationLength === 1) {
return permutationOptions.map((permutationOption) => [permutationOption]);
}
// Init permutations array.
const permutations = [];
// Get smaller permutations.
const smallerPermutations = permutateWithRepetitions(
permutationOptions,
permutationLength - 1,
);
// Go through all options and join it to the smaller permutations.
permutationOptions.forEach((currentOption) => {
smallerPermutations.forEach((smallerPermutation) => {
permutations.push([currentOption].concat(smallerPermutation));
});
});
return permutations;
}