Feedback and Questions

I ran into a puzzle that I solved using what I call "double Medusa". I don't use colors, it confuses me, I use letters. A/B instead of colors. When A/B does not solve the puzzle, I go to C/D, E/F if necessary. Today I found a puzzle that I solved when A/B and C/D occupied the same cell in two different places indicating that D could not be correct because it occupied cells containing and A and another with a B. All D's are eliminated. Manual testing confirmed.

Is this new? Did I do good?

A strange constant: The Daily Sudokus on Wednesday and Thursday are rated as tough - and I can't solve the Wednesday puzzle and have no problem with the Thursday issue.

Any explanation ... ?

Wow!! I input an Expert grade puzzle and tool pointed to the critical clue, the way a guide does.

Hi Andrew,

If you please could check why the grader is giving this soduku a 41 ("Gentle/Easy'). I was cracking my head trying to figure why I was taking so much time on a easy sudoku, but I found the solution uses a Y-wing, so it makes sense now.

Love the solver, it helps a lot.

Thank you

Hi Andrew:
Many thanks regarding you site. The sudoku methods are really outstanding.
This comment is regarding the killer sudoku solver which I applied to a hard problem that I got off the net.
The original problem:

https://www.sudokuwiki.org/killersudoku.htm?bd=122212221113313341221221441331121112334444422311121122122122133123313311144412221,121100000814000019000008000013001400160018150024000000180000000000000016000033000000000000001900001718000000180800000000001200000017000703001800001600000013000000

I stepped throught the solver until it ran out of known strategies.
When the solver got stuck we had candidates:
C4:1234568, E3:3456789, E4:3456789
G1:23456789, G2:1234, G3:1234

It is possible to make progress in this position:
Firstly, the points C4, E3, E4 total 19 as the total of all cages that intersect the rightmost five columns exceeds 45*9 by 19. This means that E3~3 since otherwise C4 and E4 would total 16 and have to be 7 and 9. This is impossible since C4 cannot be 7 or 9.

Also, the total of G1,G2,G3 must be 10 since the total of all cages that intersect the bottom two rows is 100. Since G2,G3 are both 1,2,3,4 G1 must be 5,6 or 7.

I'm sure that once the solver handles this type of situation it will noticably improved.

Dear Andrew,
I'm a huge fan of yours. Thanks for this fascinating website. I would appreciate it if you could clarify two things for me:

1- How the grading system works? Take a look at these three sudokus please:

920000030706000000000280605000038006000921000500740000803072000000000903060000012

701040906000000050609005000000100309080090020907006000000400703070000000403080105

009700050007050000100306970000500030200070009090004000081407006000020400030001700

First one is dubbed Extreme (score: 546), second one is considered Very Hard (score: 592), and third one is again Extreme (score: 687). How is that possible? Generally speaking, which one should I consider the most reliable? The score, or the Extreme/Very Hard/etc. descriptions?

2- This puzzle (010700400200050070000900050009008002003090600700400300070000000060010900008006030) has been dubbed Extreme Grade, Overall Score: 1199, with 57 steps to solve. However, if you remove 3 from F7, it'll still be standard, Extreme puzzle, but the overall score will reduce to 645, with 42 steps to solve. How is that possible? How come removing a clue makes the puzzle easier?

Thanks for your time! Really appreciate it.

I sometimes use the Windoku Solver to evaluate windokus. I have one (from e-sudoku.fr/windoku.php, number J3981) which I suspect has no solution. Windoku solver says "Or it has multiple solutions (check with [Solution Count])." But there doesn't seem to be a "solution count" button on the "windoku solver". I tried "Solve Path", and I had
"Solver by Andrew Stuart, version 2.30, 23-Apr-2023
LOAD PUZZLE
Clues: 19
Final Score: 0
Grade: Unknown"
It shows 18 steps, but I'm not sure what this means. Does "Final score: 0" mean there is no solution? Or what is the "Solution", which appears to show the numbers that the solver is able to find, plus the original clues, of couse.
Yours,
-- Owen

Hi Andrew,
I can´t open the German website any more - there ist alway Error 404.
So i´m missing one str8ts a day (the second one of the classical player) and nearly even worse: I can´t post any solution times or contact my "str8ts-community"
As someone (whose name should not be used) once said: very sad!
I hope the problem can be solves soon.
Greetings from Germany
str8ts

Many thanks for your Killer Sudoku Solver. I have been doing them for years and soon realised my limitations - can do Saturday Guardian and Observer but maybe require 2 or 3 shots at it. I was really stuck on 9/4/23 Observer puzzle - I had 4 attempts and none worked. Setting it up here was really easy - and you solved it - absolutely brilliant. I now have to work out how I went wrong - and you have given me a great start. HS.

The algorithm of the solver displays the first solution it found at a step. In my point of view, it should be interesting to know the other possible solution. Because for example, sometimes i found an AIC and when i compare with the solver, the algorithm found another AIC.
Thanks for this very good site.
Kader