Permutations without recursive function call

Question

Requirement: Algorithm to generate all possible combinations of a set , without duplicates , or recursively calling function to return results.

The majority , if not

Answer 1

I think this post should help you. The algorithm should be easily translatable to JavaScript (I think it is more than 70% already JavaScript-compatible).

slice and reverse are bad calls to use if you are after efficiency. The algorithm described in the post is following the most efficient implementation of the next_permutation function, that is even integrated in some programming languages (like C++ e.g.)

EDIT

As I iterated over the algorithm once again I think you can just remove the types of the variables and you should be good to go in JavaScript.

EDIT

JavaScript version:

function nextPermutation(array) {
    // Find non-increasing suffix
    var i = array.length - 1;
    while (i > 0 && array[i - 1] >= array[i])
        i--;
    if (i <= 0)
        return false;

    // Find successor to pivot
    var j = array.length - 1;
    while (array[j] <= array[i - 1])
        j--;
    var temp = array[i - 1];
    array[i - 1] = array[j];
    array[j] = temp;

    // Reverse suffix
    j = array.length - 1;
    while (i < j) {
        temp = array[i];
        array[i] = array[j];
        array[j] = temp;
        i++;
        j--;
    }
    return true;
}