def selection_sort(arr)
  n = arr.size - 1

  for i in 0..n do
    # set index of min element
    index_min = i

    for j in (i + 1)..n do
      # update index of min element if element is less
      index_min = j if arr[j] < arr[index_min]
    end

    # swap current element with minimum element in array
    arr[i], arr[index_min] = arr[index_min], arr[i] unless index_min == i
  end
  arr
end

p selection_sort([1,2,3])
p selection_sort([4,2,1, 3, 5,8])