[Enumerable] positioning

Ruby
1

Hello!

I’ve got this “homework”, I should create a ruby script that is able to
combine every possible letter in an array like

%w [ a b c d e f g h i j k ]

I should finally have all the possible results printed from

aaaaa
aaaab
aaaac

…to…

kkkkk

I guess I have to use an Enumerable and play with each letter’s
position… but I can’t imagine how :-\

Any idea?

Thanks,
Leo

2

Leo,

I hope I could simplify this problem to just find all the combinations
of characters. The final printing seems not very related to the puzzle.

Here is my thoughts,

You want e.g [‘a’, ‘b’, ‘c’, ‘d’] and all the combinations of different
characters, so that means you will get:

-1 diff
a | b | c | d

-2 diff
ab | ac | ad
| bc | bd
| cd
-3 diff
abc | acd
| bcd

-4 diff
abcd

You see the pattern? So it is quit easy to make an iterative algorithm
to find these combinations. Or I think you might use recursive idea to
find the answers if you put it this way:

  • Of all the 2 chars combinations that start with ‘a’, the second char
    must be from rest of the array. This way, e.g. [‘a’, ‘b’, ‘c’, ‘d’] will
    first find ‘cd’ then ‘bc’, ‘bd’ then ‘ab’, ‘ac’, ‘ad’

Hope that’s what you want…

3

Hello!
Uhm, what I’m trying to do is to have all the possible combination even
including the same character more and more time in the so generated
word.

So, something like

array = %w[ a b c d ]

aaaa
aaab
aaac
aaad
aaba
aabb

…

and so on.

4

Wow Hans, I guess you learn something new everyday. :stuck_out_tongue:

5

did you want?

array.repeated_permutation(4).map(&:join)