Writeup: https://kumaus.github.io/HE-2019/
Homepage: https://github.com/hackyeaster/he2019_writeup
The challenges for this great event are currently not accessible, but will hopefully become so at some point. A lot of the older HE challenges are now hosted at https://he-archive.sieber.space/. Many thanks to Philip Sieber for organizing this grand event every year!