Step 1: Divide the number into separate digits:
0201 => 0 2 0 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
0 to 2 = 2
2 to 0 = 2
0 to 1 = 1
1 to 0 = 1
Step 3: Combine the filters to a string:
2 2 1 1 = 2211