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/** * Implementation of [Heap's Algorithm](https://en.wikipedia.org/wiki/Heap%27s_algorithm) * for generating permutations. * * @param {Array} elements any type of data * @returns {Array<Array>} array of permutations */function permutationsHeap(elements) {    const indexes = new Array(elements.length);    const permutations = [elements.slice()];
    for (let i = 0; i < elements.length; i++) {        indexes[i] = 0;    }
    for (let i = 0; i < elements.length; ) {        if (indexes[i] < i) {            // At odd indexes, swap from indexes[i] instead            // of from the beginning of the array            let swapFrom = 0;            if (i % 2 !== 0) {                swapFrom = indexes[i];            }
            // swap between swapFrom and i, using            // a temporary variable as storage.            const temp = elements[swapFrom];            elements[swapFrom] = elements[i];            elements[i] = temp;
            permutations.push(elements.slice());            indexes[i]++;            i = 0;        } else {            indexes[i] = 0;            i++;        }    }
    return permutations;}
export default permutationsHeap;