How to combination/permutation in ruby?

Question

I\'ve this familiar question that looks like permutation/combination of the Math world.

How can I achieve the following via ruby?

badges = \"1-2-3\"
         


        

Answer 1

Array#permutation(n) will give you all the permutations of length n as an Array of Arrays so you can call this with each length between 1 and the number of digits in badges. The final step is to map these all back into strings delimited with -.

badges = "1-2-3"

badges_split = badges.split('-')

permutations = []

(1..badges_split.size).each do |n|
    permutations += badges_split.permutation(n).to_a
end

result = permutations.map { |permutation| permutation.join('-') }

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Update: I think Alex's use of reduce is a more elegant approach but I'll leave this answer here for now in case it is useful.