selection sort :)

selection.rb

def selection_sort(array, start_idx=0)
  smallest_value, swap_idx = nil, nil

  for idx in start_idx..(array.size - 1)
    val = array[idx]
    if smallest_value.nil? || smallest_value > val
      smallest_value = val
      swap_idx = idx
    end
  end

  if swap_idx.nil?
    array
  else
    array[start_idx], array[swap_idx] = array[swap_idx], array[start_idx]
    selection_sort(array, start_idx + 1)
  end
end