How I Created my Book

I wrote a C program to create sudoku puzzles in 2012. It uses a natural order tree search as described in Computer Science: A First Course, by Forsythe, Keenan, Organick, and Stenberg.

Using a Linux shell script I ran this program repeatedly and graded each puzzle using Hodoku. I saved puzzles with a Hodoku grade between Hard (1000) and Hard (1999) and rejected the rest. I ran my program just over 8000 times to create the 400 puzzles which appear in my book.

I then wrote a Python  program to put the puzzles into a PDF, which Amazon print for me through KDP. This has allowed me to publish my book with no up-front costs. Copies of my book are printed on demand so I do not have to hold any stock either. Unfortunately this makes my book slightly more expensive than a similar book from a newsagent or supermarket as I do not have their economies of scale. I do not regard this as too much of a problem as I have never seen a book like this for sale anywhere else.