selection_sort.rb

def selection_sort(collection)
  length = collection.length

  for i in 0..length - 2
    min_index = i

    for j in (i + 1)...length
      if collection[j] < collection[min_index]
        min_index = j
      end
    end

    tmp = collection[i]
    collection[i] = collection[min_index]
    collection[min_index] = tmp
  end
  collection
end