Definition: 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.
Input: [285, 252, 257, 487, 236, 465, 184, 172, 30, 340, 339, 67, 462, 483, 489, 205, 456, 66, 84, 39]

[285, 252, 257, 487, 236, 465, 184, 172, 489, 340, 339, 67, 462, 483, 30, 205, 456, 66, 84, 39]