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 Killer Sudoku Solver Please report any bugs and feedback welcome
 Click to edit candidates or enter a solution: Show Candidates

 1 2 3 4 5 6 7 8 9
 Auto Clear
Clues+Solved: 0/81
 Pick an example here Gentle Example 1 Gentle Example 2 Moderate Example 1 Moderate Example 2 Tough Example 1 Tough Example 2 Diabolical Example 1 Diabolical Example 2 Extreme Example 1 Extreme Example 2
Help on Killer Definitions used here for transporting puzzles
Quick help: Using this Solver

You can pick examples from the list above. Click on Take Step to step through the solution. Unknown squares are filled with 'candidates' - possible solutions.
Any cells that are reduced to one possible candidate are solved.

You can enter a new Killer puzzle using the new 'designer' - click on "Enter new Killer". Once you fill in the clues and set up the cages correctly it can be solved.

Unlike the other solvers you can only edit the main board when solving. The small board only displays the clues.
 A B C D E F G H J
 Version 2.26.4 See Strategy Overview documentation Coordinate system: Letter/Number rYcX
 1 2 3 4 5 6 7 8 9
 Check for Solved Squares Show Possibles 1: Hidden Singles 3: Naked Pairs/Triples 4: Hidden Pairs/Triples 5: Quads 6: Killer Combinations (easy) 7: Innies and Outies (1 cell) 8: Pointing Pairs 9: Box/Line Reduction Tough Strategies 10: Cage Splitting 11: X-Wing 12: Simple Colouring 13: Y-Wing 14: Innies/Outies (2+ cells) 15: Killer Combo's (hard) 16: Cage/Unit Overlap 17: Cage Compare 18: Rectangle Elimination 19: Swordfish 20: XYZ Wing Diabolical Strategies 21: X-Cycles 22: XY-Chain 23: 3D Medusa 24: Jellyfish 25: WXYZ Wing 26: Aligned Pair Exclusion Extreme Strategies 27: Grouped X-Cycles 28: Finned X-Wing 29: Finned Swordfish 30: Altern. Inference Chains 31: Sue-de-Coq 32: Digit Forcing Chains 33: Nishio Forcing Chains 34: Cell Forcing Chains 35: Unit Forcing Chains 36: Almost Locked Sets 37: Death Blossom 38: Quad Forcing Chains "Trial and Error" 39: Bowman Bingo

## Welcome to this Killer Sudoku Solver

Killer Sudoku solver has quite a complicated definition and I hope the method I've created to enter a puzzle works for most people. The independent 'Designer' handles the entering of the clues and cages. Keeping this separate and being able to (loosely) validate the entry should allow puzzle solvers a fairly quick way of setting up the puzzle for solving. I hope you agree and I'd love to hear your feedback.

You should also be aware of the Killer Cage Convention.

New in version 2.26.4 (5th August 2024)
New addition to Innies and Outies.
This has prompted me to recalibrate the scoring. I've noticed that simple pair combinations for 2-cell cages rarely get evaluated unless there is only one combination. The so-called "killer combinations (easy)" in the solver. Moving the 2-cell from the "killer combinations (hard)" to the "easy" has changed scores a good deal and I need to restock the player and reset the calibration. This change avoids mid-level strategies being applied to 2-cages which on the face of it ought to have been reduced earlier with quite obvious pair combinations. I'd be interested if people think the 9x9 Killer puzzle has got harder or easier from tomorrow onwards.

New in version 2.24 (July 2024)
Better New/Modify Killer designer which now remembers partially designed puzzles. Added import from a string definition.

New in version 2.13 - 2.16 (May 2024)
Added the ability to transport a Killer puzzle in progress with all the solved cells and candidates. Available in the [Email this Board] button.

New in version 2.16 (October 23th 2023)
Important update thanks to JohnNoneDoe who supplied an example, I have improved the Innies and Outies strategy. Particularly outies which he observed, do not need to obey the Dog-leg restriction on the pseudo-cell they create. This improvement has a large effect on hard Killers improving the hit rate (I hope). I have also changed how a block displays so as not to override the cell colours.

New in version 2.09 (October 25th 2022)
Made cells with incorrect numbers look better and moved popup alert to results box; new catch for cages not adding up to the clue.

New in version 2.06 (September 8th 2017)
For Naked Pairs in a cage I've added the case where the two cells are diagonally positioned.

New in version 2.03 (August 29th 2015)
Killer Cage Convention will now clear off candidates in 'dog-leg' cages early in the list of checks - as and when solution numbers are found.

New in version 1.91 (October 16th 2012)
Re-wrote the Innies/Outies algorithm to look for innies with more than one cell covering several sticking-out cages. Re-ordered the strategies to balance them against new calibrations.
Added Cage Comparison to the killer strategies.

New: Version 1.02 (June 13th 2009)
Killer Sudoku Solver released

 Email your puzzle to a friend Copy and paste the contents of the green box into your email program and send it off. The links contain the puzzle which will load when your friend visits the Sudoku Solver.
Solver created on 30-May-2009.