Added editorial for ZCO 2022 - Vacation

[Sanjay-Muthu]

Added editorial for ZCO 2022 - Vacation

[avighnac]

Hi, unfortunately there are several issues here:

1. You should link to the guide's resources for prefix sums (since these exist) instead of USACO guide's.
2. You have omitted the use of latex in several places.
3. The image(s) used are, again, pretty different from the images used in the rest of the guide.
4. You can't use CodeChef links for your code, you should paste it here instead.

Thanks, and I'll only be able to merge this if these issues are fixed.