Instructions: 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: [339, 229, 429, 239, 321, 334, 115, 36, 456, 269, 402, 483, 230, 453, 378, 262, 299, 227, 238, 268]
Output:
[339, 229, 429, 239, 321, 334, 115, 483, 456, 269, 402, 36, 230, 453, 378, 262, 299, 227, 238, 268]