merge sort

def merge_sort(arr)
  return arr if arr.size <= 1
  
  left, right = halve_array(arr)
  left_part   = merge_sort(left)
  right_part  = merge_sort(right)

  array = []
  offset_left_part  = 0
  offset_right_part = 0
  
  while offset_left_part < left_part.count && offset_right_part < right_part.count
    a = left_part[offset_left_part]
    b = right_part[offset_right_part]
    
    if a <= b
      array << a
      offset_left_part += 1
    else
      array << b
      offset_right_part += 1
    end

    while offset_left_part < left_part.count
      array << left_part[offset_left_part]
      offset_left_part += 1
    end
 
    while offset_right_part < right_part.count
      array << right_part[offset_right_part]
      offset_right_part += 1
    end
 
    return array
  end
end
 
def halve_array(arr)
  median = (arr.size / 2).round
  [arr.take(median), arr.drop(median)]
end
 
a =[3,5,2,45,41,500,41]
p merge_sort(a)