Treadmill Sort

treadmill_sort.rb

# -------------------------
# Treadmill Sort
# -------------------------
# written in ruby 2.5.3
# recursive
# -------------------------

# reduces an array into its lowest value item
def min arr
  if arr.length > 1
    arr[0] < arr[1] ? min([arr[0]].concat(arr.drop(2))) : min(arr.drop(1))    
  else
    arr[0]
  end
end

def treadmill (arr, min=min(arr))
  
  # if there are enough items to sort
  if arr.length > 1
    
    # if the first item is the smallest
    if arr[0] == min
      
      #take that item and concatenate the next round
      [arr[0]].concat(treadmill(arr[1..-1]))
      
    # if the first item is not the smallest
    else
      
      #call next round with first item moved to the end
      # as no items are removed the current min will be used for the next round
      treadmill((arr[1..-1]).concat([arr[0]]), min)    
    end
    
  #if there are not enough items to sort
  else
    
    #return array 
    arr
  end
end

# -------------------------
# p treadmill *array goes here*