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@@ -25,7 +25,7 @@ So, here's my day-by-day opinion on how this year went for me.
 *  **Day 17** (no solution).  *Find the period in the pattern of falling rocks.*  I'm sure this one isn't too bad, but I was feeling too burnt out by Day 16 to give it more than a token try.
 *  **[Day 18](https://github.com/hunkyjimpjorps/AdventOfCode/blob/main/2022/day-18/day-18.rkt)**.  *Find the surface area of an irregular rock.* A nice straightforward volume-scanning problem, and another opportunity to use my sparse matrix data type.
 *  **Day 19** (no solution).  *Pick the best plan for building mining robots.*  Another heuristic search problem, so I skipped this one since I was still failing at day 16 part 2.  Picking out an optimized robot building strategy had more moving parts than I knew how to deal with.
-*  **[Day 20](https://github.com/hunkyjimpjorps/AdventOfCode/blob/main/2022/day-20/day-20.rkt)**.  *Repeatedly shift elements around in a circular array.*  Singly-linked lists are terrible for repeated arbitrary access, but I don't care.  I figured out an algorithm that worked and I was happy enough with that to accept it and move on.  After the previous streak of problems, I was just happy to figure out day 2 on my own.
+*  **[Day 20](https://github.com/hunkyjimpjorps/AdventOfCode/blob/main/2022/day-20/day-20.rkt)**.  *Repeatedly shift elements around in a circular array.*  Singly-linked lists are terrible for repeated arbitrary access, but I don't care.  I figured out an algorithm that worked and I was happy enough with that to accept it and move on.  After the previous streak of problems, I was just happy to figure out Part 2 on my own. (There was a modulo math trick element to Part 2 here as well, but this one was a lot more obvious to spot.)
 *  **[Day 21](https://github.com/hunkyjimpjorps/AdventOfCode/blob/main/2022/day-21/day-21.rkt)**.  *Figure out what to shout in the monkeys' math game.* I have a feeling the intended solution for Part 2 of this one was to build the expression tree and backtrack through the operations to calculate the unknown value.  However, I just blindly started evaluating the result for various guesses and discovered through trial and error that the relationship between the guess and the result is linear, so all you need for part 2 is two guesses, their corresponding results, and some algebra.  It's fun to accidentally discover simple solutions to complex-looking problems.
 *  **Day 22** (no solution).  *Something involving walking around on a map.* I skipped this one because of the flu.  C'est la vie.
 *  **[Day 23](https://github.com/hunkyjimpjorps/AdventOfCode/blob/main/2022/day-23/day-23.rkt)**. *Cellular elfomata.*  Another AoC staple, though later than usual.  I think the story got in the way of the problem description a little bit here, but once I talked through the rules with someone else it was a straight shot to the solution.