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Hello fellow Rubyists

The following code is a recursive combination generator written in Ruby. Given an array of objecs/numbers/..etc, it will return an array of all possible combinations . This originally started out using two functions that contained looping logic in them. It worked well, however I just wanted to stretch myself a bit and try my hand at doing it recursively. Below is the result of my efforts. I hope this helps with anything you may be working on… enjoy!

#javazquez.com

#tail is a clone because of Ruby's passing by reference and shift

#returns an unsorted array

def combination(ary,head=[])
  return ary if(ary==[] )
  head << ary.shift
  tail = ary.clone
  tmp=[]
 if(tail.length>=1)
    tmp+= combination(tail[1..(tail.length)],head.flatten)+
                       combination(Array(tail[-1]),head.flatten)
    tmp+=combination(tail[2..(tail.length)],head.flatten) if(tail[2])
  else
    tmp += combination(tail,Array(head[0]))
  end
  tmp += combination(tail, []) +combination(ary,head.flatten)
  return (tmp << head).uniq
end

combination([1,2,3,4]).sort.each{|it| puts it.inspect  }
#  combination(['A','B','C','D','E','F','G','H','I','J']).sort.each{|it|  puts it.inspect}
#  combination(['A','B','C','D']).sort.each{|row| puts row.inspect}

----output--

[1]
[1, 2]
[1, 2, 3]
[1, 2, 3, 4]
[1, 2, 4]
[1, 3]
[1, 3, 4]
[1, 4]
[2]
[2, 3]
[2, 3, 4]
[2, 4]
[3]
[3, 4]
[4]

Ruby, code algorithm, algorithms, code, combinations, fun, Generating, math, Programming, recursion, recursive, Ruby