Maxie is the largest number that can be obtained by swapping two digits, Minnie is the smallest. Write a function that takes a number and returns Maxie and Minnie. Leading zeros are not permitted.
maxmin(12340) ➞ [42310, 10342]
maxmin(98761) ➞ [98761, 18769]
maxmin(9000) ➞ [9000, 9000]
# Sometimes no swap needed.
maxmin(11321) ➞ [31121, 11123]N/A