Category: blog

It has taken over 23 days (23.7 to be exact) to shatter the last Sudoku record. Around 6:37 PM Eastern time, our Sudoku solver completed an 9025×9025 puzzle (box dimension 95) with over 39 million blanks. That’s almost 19 blanks/second on average which is slower than the 22 blank/sec achieved solving the 8100×8100 Sudoku. That’s…

On September 18, 2024, a 7225×7225 Sudoku (box dimension 85) with 25M blanks was solved in 10.7 days. That is 27 blanks per second on average. In fact, that isn’t how the solution works. Only a few blanks are solved in the first rounds of working the puzzle. Near the end thousands of blanks get…

Yet another week to break the record. This time we solved Sudokus with box dimensions of 75 (5625×5625 grid) and 80 (6400×6400 grid). Each puzzle took 6-7 days to solve. Observers might note that the expected trend to solve the Sudokus seems to have changed. I reduced computational times by breaking the problem into sub…

What do you mean, passively? I let the computer crunch on larger Sudokus while I was on vacation. On August 3, 2024 a Sudoku with a box dimension of 65 (4225×4225 grid) with 8.6 million blanks completed in 1.5 days. A few weeks later, a Sudoku with a box dimension of 70 (4900×4900 grid) with…

In the quest to speed-up processing of Sudokus, we’re wondering – does it make sense to recode Sudoku solving using CUDA? Before you do that, it makes to optimize what we have already and do some preparatory work to smooth the transition to CUDA if needed. Remember – we’re not trying to all Sudokus of…

Background A few years ago I modified backtracking C code from Daniel Beer to generate and solve larger Sudoku puzzles (up to 1024×1024 grids). The elapsed time to solve larger and larger Sudoku puzzles climbed so quickly I started to look at alternative algorithms for solving and creating large Sudokus. The current solvers use single…

To save time, I needed a way to create a valid Sudoku puzzle of arbitrary size (square for now) without having to check whether or not there was a single solution. It turns out that it is possible to design a square Sudoku puzzle of arbitrary size. Even better if the puzzle requires singles strategies…

Box Dimension Grid Size Time 95 9025×9025 23.7 days 90 8100×8100 16.83 days 85 7225×7225 10.7 days 80 6400×6400 6.84 days 75 5625×5625 5.95 days 70 4900×4900 6.73 days 65 4225×4225 1.51 days 60 3600×3600 68,985.3 sec 55 3025×3025 37,700 sec 50 2500×2500 18,951.9 sec 45 2025×2025 8,720.5 sec 40 1600×1600 3,672.9 sec 35 1225×1225…

Okay, we think it’s largest ever, but at least it definitely is big. On July 24, 2024 a Sudoku (3600×3600 grid) with 6.2 million blanks was solved in 6 days. A few days before on July 18, 2024 a Sudoku (3025×3025 grid) with 4.4 million blanks was solved in 2.5 days. Want to see a…

Find naked or hidden singles is the most basic strategy for solving a Sudoku. But how do you code a routine to do what a human does? First, let’s understand what a human does. See the learn sudoku page to see an example. You need to find missing numbers in a row, column, and block…

Between 1998 and 2021, TSF Inc. was a small business that did consulting work in oil and gas and food research. Strange, I know. Since 2021 we disbanded our for-profit enterprise and now focus on volunteer efforts – generally educational and uplifting.

Check out A Fan of Sudoku on youtube! Why does anyone find Sudoku appealing? Mental Workout: Sudoku is a brain teaser that requires logical thinking, problem-solving, and critical thinking skills. For me, it’s a way to solve something that involves one of my favorite things: numbers. Sense of Accomplishment: Completing a Sudoku puzzle, especially a…