Clueless Special

Ruud · Site Admin

Normally, I stay away from the weird and exotic sudokus, so you may find it strange to find a post by me here.

However, I've created a new variety that may appeal to a lot of Sudoku addicts. There is a central Sudoku that you need to solve, but you have no clues to start with. Each of the 3x3 boxes is placed in a separate 9x9 Sudoku that you need to solve. Most of the time, you will only be able to pass on sparse eliminations through the central clueless sudoku. All 9 supporting sudokus are needed to solve the clueless one.

I had a lot of fun creating it. I hope you guys have fun solving it.

The little monster can be found here: www.sudocue.net/clueless.php

Please send some comments back, so I can determine whether of not I should create another one...

Ruud.
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Miles · Posted: Thu Feb 16, 2006 8:31 am Post subject:

Very interesting Wink

Ruud · Site Admin

A brand new Clueless Special can now be found at www.sudocue.net/clueless.php (the first one is still available in case you missed it)

The bar has been raised a little. Try to solve this monster without bifurcation... Twisted Evil

Ruud.
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Meet me at sudocue.net

Ruud · Site Admin

As a teaser, I will post a Clueless Special exclusive to this forum. If you need to refer to it, call it #4c.

The mission:

This puzzle has 9 constituent Sudokus. The central 3x3 boxes in each of these 9 Sudokus (colored blue), in the configuration of the constituent puzzles, form a 10th Sudoku, which is completely clueless. None of the constituent puzzles can be solved independently, you need to feed information back and forth using the 10 puzzles to solve the Clueless Special as a whole.

This is the Clueless Special #4c:

In pasteable format:

PeteTy · Posted: Mon Aug 07, 2006 9:24 am Post subject: clueless

there are several of those clueless specials that I cant solve without bifuraction...
but i havent done triples quads hidden twins and xwing xy wings in my program yet.

i can get the easy grids pretty well knocked down then paste into Argus SS
to find those 'Advanced things"

as I improve my program .. there are more and more of the grids i paste where argus says 'no hints available' he resorts to bifuracation and sometimes the solution his leads to leads to a dead end chain ... theres got to be a way to only follow the correct chain solvable by the good chains
but i have a feeling the eliminations i make in the blue squares don necessairly reflect the entire grid or all 9 of the component puzzles..
I had a lot of possibilitys removed that shouldnt have been.

Mauricio · Posted: Mon Sep 11, 2006 9:19 pm Post subject: Interesting

Hi Ruud

How do you create this clueless puzzle?
I think tou use a backtracking algorithm, right? Perhaps DLX.

How long it takes to create it?

Mauricio

Ruud · Site Admin

Hi Mauricio,

Clueless puzzles are created in the following way:

1. Create 30 to 50 standard Sudokus with the givens in a fixed pattern. Some of the cells in the center box also contain a given, so each puzzle has a unique solution.
2. Create a random solution for the "blue" cells.
3. Pick 9 random sudokus from step 1, relabel the digits to match the central solution, clear the givens in the center box and put the puzzles together in the Clueless format.
4. Solve the Clueless puzzle in step 3 using the selected solving techniques (settings depend on the difficulty)
5. Repeat steps 3 & 4 until a good puzzle is found.
6. Restart from step 1 (using a different pattern) when no good puzzle is found.

It takes my computer 5-10 minutes to find a decent Clueless using this method.

Ruud
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Meet me at sudocue.net

Mauricio · Posted: Thu Sep 21, 2006 1:53 am Post subject:

Hi Ruud, thanks for the answer.

I assume you check for the unicity of the puzzle in step 4 (unless you do not use any uniqueness technique to solve the puzzle).

I have just had an idea for a new kind of sudoku puzzles, something between a clueless special and disjoint groups (it is not a clueless special with disjoint groups). Can you guess what it is?

I'll post it when I modify my sudoku creator to create one (if they do exist).

Ruud · Site Admin