[foxes]

As someone who has studied maths Proj Euler is infinitely more interesting especially in the harder questions. For me, most of time spent in advent of code is basically about parsing a blob of text. Project Euler inspires much more interesting ideas. Mostly it is number theory and algebra.

[smcl]

The same could be said for actual advent calendars - if you go around any supermarket you could get much better chocolate for a kid than any advent calendar will have and it'll doubtless be cheaper too. But when you're a certain age there's something particularly magical about the experience of waking up in the morning, finding the little door for today, opening it up and having the little (vaguely) christmas-themed chocolate shape.

As an adult, I have to say that for me doing AoC brought back a little of that magic. It helped that the problems unlocked at 6am in my timezone so I'd wake up, hack on the problem for an hour or so then walk my dog and get ready for work. It was also nice having a collective experience, knowing that not only 5-6 of my colleagues but thousands of other people across the globe were all going through the same problem at the same time. I really liked that feeling.

So yeah Project Euler has very compact, well-written, well-designed, challenging problems in spades ... but AoC is a very specific sort of event that I must admit I look forward to more and more each year :-)