In this task, you are given a list of unique integers you need to swap the positions of maximum and minimum element in the list and return the updated list.

[243, 171, 26, 446, 109, 477, 285, 67, 193, 123, 335, 288, 357, 135, 51, 464, 257, 447, 208, 240]
[243, 171, 477, 446, 109, 26, 285, 67, 193, 123, 335, 288, 357, 135, 51, 464, 257, 447, 208, 240]