This problem holds a special place in my heart. When I first discovered PE* I checked the latest available problem, which was 202 that week. I remember thinkin

This problem holds a special place in my heart. When I first discovered PE* I checked the latest available problem, which was 202 that week. I remember thinking at the time that it was impossible to solve. Fast forward a couple of years and a lot of solved PE problems. I took another go at 202 and I finally figured it out. The feeling of accomplishment I felt then... *through an xkcd comic (https://xkcd.com/353/ https://xkcd.com/353/). The alt text mentions 20 small problems, which are problems from PE (IIRC this was specified in the now-defunct xkcd blog)