Yes that's a brilliant article. I do not think it is in the book yet?

I used a poor man's version to solve a puzzle where one arranges polymino pieces on a grid spelling out the date [1]. No pointers, just keeping track of deleted rows and columns in the recursion.

It is not at all obvious that all 366 days can be solved. To my dismay all of them can be solved in multiple ways - as a human I find some days quite tricky.

[1] https://metterklume.github.io/puzzle/2024/12/24/calendar-puz...

It is in the book, it’s a big part of 4B, which was published in 2022. The main topics are backtracking, exact cover using Dancing Links and satisfiability. It’s my favorite volume of the whole bunch.