permutator | Cartesian product , Combination , and Permutation library

How to set the length of a generated permutation?

for example:

permutator(['as', 'dd', 'ff'], 2);

This is what I got so far:

I just wanted to find out what is the reason that the python shell doesn't give the output i expect for the following recursive code:

I wanted to create a function that returns a data structure with all possible combinations for a certain group of numbers: e.g.: for [1, 2, 3] return [[1], [2], [3], [1, 2], [2,1], ..., [1, 2, 3], [2, 1, 3], ...[3, 2, 1]].

I understand that c and p are some kind of vector of &integer, but I cannot find a way to save them into an array or vector. I was trying to save it as a vector of vectors since I do not think it is possible to save them as a vector of arrays, since the arrays have different sizes. It's also not possible as an array of vectors since I do not know the number of combinations at the start.

How can I store all c and p in a data structure so that it can be returned and used outside?

I'm doing a task named Simple Fun #159: Middle Permutation on codewars.

The description is:

You are given a string s. Every letter in s appears once.

Consider all strings formed by rearranging the letters in s. After ordering these strings in dictionary order, return the middle term. (If the sequence has a even length n, define its middle term to be the (n/2)th term.)

This is my code:

I was working on problem 24 on project euler, after a couple of days researching and thouroughly understanding what backtracking is and how to implement it, I finally got my permutator to work, here it is:

Here is the combination / permutator generator function that uses any number of lists with values and any length of template strings. The generator creates corresponding lists with combinations / permutations of values matching the template string. The answer was given by a colleague here: https://stackoverflow.com/a/48121777/8820330