The time I was ready to submit my solution, I thought this kata should be ranked as 4 kyu. However, after reading the cleverest solution, I realize I still need to learn more algorithm and method.

It means if 0 comes after 9, 0 can be seemed as 10, but 1 shouldn't come after 10

This Kata reminds me of a question:
a=[1,2,3]
b=a
a.pop()

The result of b is [1,2]
So how can we store a list?