Blog posts with problems to get your brain going! You get a new problem every fortnight and the solutions are published later.
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The next problem is scheduled for Sunday, 18th of October, around 19h GMT.
You may notice some problems are missing... I'm still migrating articles from my old blog.
This post's problem is a really interesting problem I solved two times. The first time I solved it I failed to prove exactly how it works... then some years later I remembered the problem statement and was able to solve it properly. Let's see how you do!