May 2026: Arch Madness

Well, my run of being fairly terrible at the grid-based Jane Street puzzles continues. Sure, I placed relatively highly, but the amount of time I had to spend on the puzzle disqualifies me from any pride, and I was losing my mind so much that I had to ask Fred Vu to confirm parts of my grid and tell me which other parts had mistakes. One positive I can take away from this month’s puzzle was that I remained convinced that solving by hand was the best strategy, and never became tempted to try and brute-force the puzzle with code as I sometimes used to do. However, I once again fell victim to letting little mistakes go unnoticed for too long, and letting myself become so convinced of certain decisions that I couldn’t see clear alternatives sitting in plain sight. Looking forward to the next grid-based puzzle so I can challenge myself to learn from these mistakes and improve at this style of puzzle.

Stats:

Difficulty: 6/10

Enjoyability: 4/10

Leaderboard Placing: 25/599

The approach:

I have very little to say about this one, except that you just need to start placing arcs and follow your gut. Some parts of the grid are clearly very constrained, and I started by filling out the region surrouding the two nines, the 25, and the 15 in the top-right. Following this, the regions with score 21 and 27 were very easily determined, which paved the way for the bottom left-hand side of the grid to be filled, and then finally the bottom-right. It was always clear that the region with score 288 would need to span most of the board — filling in the spaces between other regions — and making room for this always motivated my decisions. My biggest stumbling block was getting stuck in the mindset that the region with score 63 had to be of a certain shape, not noticing that a) this shape couldn’t be made to have integral area, and b) this shape didn’t leave enough room for the region with score 288. If I hadn’t made this simple mistake, I would have had a much better time solving this month’s puzzle. Lesson learnt to always keep the mind flexible when solving this kind of puzzle!