In the ICPC (International Collegiate Programming Contest), each team is allowed to bring up to 25 pages of printed material. There are many great codebooks out there such as KACTL, but I prefer to write templates by myself. I am currently using verification-helper to manage my codebook. What makes verification-helper so useful is that it lets you create tests for your templates, which get run on Atcoder and Library Checker problems. It also has an
oj-bundle script that merges all the templates you’ve used into your solution file.
The only missing feature is an “export to pdf” feature. This doesn’t matter so long as ICPC contest are online, but I’ll have to worry about this in the future.