Friday 31 December 2021
Real Word Gogen no 7
Add the 25 letters between A and Y to the grid above. Each one should appear exactly once. When you have finished, you must be able to spell the following words moving horizontally, vertically or diagonally around the grid:
BAIT, DECK, EQUATION, FLIGHT, FRY, IONS, JUMP, NEW, ONCE, PAT, SOIL, VEX.
Thursday 30 December 2021
A Samurai Sudoku Puzzle from Morocco
Hamza Dhoum, a member of my Sudoku Puzzles Facebook group has published a new book of Samurai Sudoku puzzles. He sent me this link to allow you to buy a copy if you wish.
Here is one of the puzzles from his book:
Tuesday 28 December 2021
Sudoku no 632 (Extreme / Unsolvable)
I set out to make an extreme puzzle and asked my sudoku creator to give me several grids all with the same solution. Once it had produced around 70, it came up with this one, which had a Hodoku grade of Extreme (6092):
I checked this grade with Andrew Stuart's grader and solver, which could not find a solution:
I clicked the Take Step button repeatedly until the solution was found and saw that Bowman's Bingo (Trial and Error) was used several times.
Sunday 26 December 2021
Saturday 25 December 2021
Friday 24 December 2021
Wednesday 22 December 2021
Sunday 19 December 2021
Tuesday 7 December 2021
Evil Sudoku Puzzles on Easybrain's Web Site and Smart Phone Applications
From time to time, members of my Sudoku Puzzles Facebook group buy a book of extreme sudoku puzzles then complain when it only contains easy puzzles. I can understand their frustration so have recently been looking at other places to find genuinely difficult sudokus.
I did a search on Google and found Sudoku.com, which is now run by Easybrain. I went to the site and asked for evil puzzles. This is one of them:
Then I reviewed the puzzle independently at Andrew Stuart's grader and solver.
The Grader button gave it a grade of Extreme / 1097.
The Solve Path button said that I would have to use several tough, diabolical and extreme strategies to solve it.
I repeated this test with a 2nd evil puzzle and got similar results.
I therefore recommend evil puzzles from Sudoku.com for people who enjoy very very tough sudokus.
I wrote this web site review using my UBUNTU laptop.
If you have an Apple device, you can download Easybrain's application for it here.
If you have an Android device, the application you need is here.
Sunday 5 December 2021
Sudoku no 626 (Diabolical)
I have recently been discussing the creation and grading of sudoku puzzles with a member of my Sudoku Puzzles Facebook group.
I make my own puzzles using a C program, which I wrote myself in 2012. This creates a valid solution then randomly removes as many clues as possible, whilst still retaining exactly one answer. I then grade each puzzle using Hodoku and/or Andrew Stuart's grader and solver (see link below puzzle).
I find that this method produces puzzles with a range of difficulties from easy through to extreme. None of my puzzles have any surplus digits.
The member mentioned above asked me to grade three puzzles for him so I submitted the first one to Andrew Stuart's grader and solver (see link below puzzle), which said it was very easy. It also had several spare digits i.e. clues which could be removed to leave a slightly more difficult puzzle, which still had exactly one solution. I have seen this from time to time in sudoku books but personally I don't like it.
I removed as many of the spare digits as possible, which created the diabolical puzzle below:
Saturday 20 November 2021
Wednesday 17 November 2021
Tuesday 9 November 2021
Tuesday 26 October 2021
Tuesday 19 October 2021
Sudoku no 621 (Diabolical)
This sudoku puzzle is very near the bottom of the diabolical category:
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Sunday 17 October 2021
Thursday 30 September 2021
Saturday 25 September 2021
Sudoku no 618 (Easy / Moderate)
Hodoku says this sudoku puzzle is easy. Andrew Stuart's grader and solver says it is moderate:
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Monday 20 September 2021
Sunday 12 September 2021
Saturday 28 August 2021
Tuesday 10 August 2021
Sunday 8 August 2021
Saturday 24 July 2021
Sudoku no 612 (Easy)
Andrew Stuart grades this puzzles as Moderate but Hodoku grades it as Easy. Personally I prefer the latter if a puzzle only has hidden singles and last candidates:
Sudoku no 611 (Diabolical)
This sudoku is towards the lower end of the diabolical range. Depending on how you go about solving it, you may meet a bi-value universal grave at the end:
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