This is the fun and annoying part of the PE problem set :-) I work on them purely for fun, and suddenly with years between. Some can definitely be a bit annoyin

This is the fun and annoying part of the PE problem set :-) I work on them purely for fun, and suddenly with years between. Some can definitely be a bit annoying, but their purity and conciseness makes it possible to store problems in your head and keep thinking about them for a while. I've never felt cheated by the problems, as often there will be several ways to solve something, and it feels really fun to shave down the running time by improving an algorithm. They are also very well stated, so there's rarely any mistake or edge case issue with them (my experience is in the first few hundred). Some problems are just fun to work out mostly through code, like Poker Hands [1] or Monopoly [2], and other more geometric ones like Magic 5-gon ring [3] or Hexagonal tile differences [4] are nice to just reason about on paper. These don't really require much specific knowledge. For problems requiring more knowledge to find useful tricks to solve the problem, I'll often load some related Wikipedia pages I can study on a flight or train ride. [1] https://projecteuler.net/problem=54 https://projecteuler.net/problem=54 [2] https://projecteuler.net/problem=84 https://projecteuler.net/problem=84 [3] https://projecteuler.net/problem=68 https://projecteuler.net/problem=68 [4] https://projecteuler.net/problem=128 https://projecteuler.net/problem=128