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.
Q: [81, 268, 174, 47, 16, 230, 165, 137, 291, 457, 188, 413, 36, 238, 454, 284, 115, 378, 356, 135]
A: 
[81, 268, 174, 47, 457, 230, 165, 137, 291, 16, 188, 413, 36, 238, 454, 284, 115, 378, 356, 135]