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.

[282, 38, 402, 29, 79, 187, 434, 308, 398, 386, 470, 358, 266, 214, 145, 115, 380, 66, 20, 136]
[282, 38, 402, 29, 79, 187, 434, 308, 398, 386, 20, 358, 266, 214, 145, 115, 380, 66, 470, 136]