Given a matrix x with n rows and m columns, return a matrix y with n rows and 2m columns, such that every row in x is sorted from low to high and then from high to low.
Example:
x = 9 2 8 1
5 4 9 8
8 9 6 9
y = 1 2 8 9 9 8 2 1
4 5 8 9 9 8 5 4
6 8 9 9 9 9 8 6
Additional test cases have been added.