Question:

Compare two version numbers version1 and version1.
If version1 > version2 return 1, if version1 < version2 return -1,
otherwise return 0.

You may assume that the version strings are non-empty and contain only
digits and the . character.
The . character does not represent a decimal point and is used to
separate number sequences.
For instance, 2.5 is not "two and a half" or "half way to version
three", it is the fifth second-level revision of the second first-level
revision.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.37