Find all the possible permutations using Ruby and recursion Ask

permutations.rb

# https://stackoverflow.com/questions/25224321/find-all-the-possible-permutations-using-ruby-and-recursion

$letters = "prtsone"

# Make permutations from letters
def permutation(string)
  return [string] if string.size < 2
    ch = string[0]
    permutation(string[1..-1]).each_with_object([]) do |perm, result|
      (0..perm.size).each { |i| result << perm.dup.insert(i,ch) }
  end
end

$permutations = permutation($letters)