

Advanced Solving Sudoku Technique


Interaction by us createclassicsudoku.com


Hard Sudoku on 03/16/2018
In the ninth 3×3 box all candidates of number 2 are confined to the seventh row. Remove number 2 from R9C9. 

Above is an example of using InteractionRowBox(a.k.a. Intersection, Locked Candidates, or Row Claim) to refine the candidate values of R9C9 (the highlighted squares in the ninth 3×3 box excluding the seventh row). Blank/Empty Squares are marked with candidate values in red. 

In the ninth 3×3 box all candidates of number 2 are confined to the seventh row, therefore number 2 cannot appear outside of the ninth box in the seventh row. That being said, R8C8 and R9C9 can remove this digit from their candidate values. Note that only R9C9 contains number 2 as a candidate value, so we can remove number 2 from R9C9's candidate values. 

Solve Hard Sudoku on 03/16/2018 in a stepbystep style  
Hard Sudoku on 03/16/2018
In the seventh row all candidates of number 8 are confined to the eighth 3×3 box. Remove number 8 from R7C7 and R7C9's candidate values. 

Solve Hard Sudoku on 03/16/2018 in a stepbystep style  
Above is another example of using Interaction(a.k.a. Intersection, Locked Candidates, or Box Claim) to refine the candidate values of R7C7 and R7C9 (the highlighted squares in the seventh row excluding the eighth 3×3 box). Blank/Empty Squares are marked with candidate values in red. 

In the seventh row all candidates of number 8 are confined to the eighth 3×3 box, therefore number 8 cannot appear outside of the seventh row in the eighth box. That being said, R7C7 and R7C9 can remove number 8 from their candidate values. 

For easy understanding, in our Sudoku solver, we call InteractionBoxRow: If in a 3×3 box all candidates of a certain digit are confined to a row, that digit cannot appear outside of that box in that row. That being said, that row outside of the block can remove this digit from their candidate values. InteractionBoxCol: If in a 3×3 box all candidates of a certain digit are confined to a column, that digit cannot appear outside of that box in that row or column. That being said, that column outside of the block can remove this digit from their candidate values. InteractionRowBox: If in a row all candidates of a certain digit are confined to one 3×3 box, that candidate that be eliminated from all other squares in that 3×3 box. InteractionColBox: If in a column all candidates of a certain digit are confined to one 3×3 box, that candidate that be eliminated from all other squares in that 3×3 box. 

How to find them?




Advanced Solving Sudoku Technique


Interaction by us createclassicsudoku.com


Hard Sudoku on 03/16/2018
In the ninth 3×3 box all candidates of number 2 are confined to the seventh row. Remove number 2 from R9C9. 

Solve Hard Sudoku on 03/16/2018 in a stepbystep style  
Above is an example of using InteractionRowBox(a.k.a. Intersection, Locked Candidates, or Row Claim) to refine the candidate values of R9C9 (the highlighted squares in the ninth 3×3 box excluding the seventh row). Blank/Empty Squares are marked with candidate values in red. 

In the ninth 3×3 box all candidates of number 2 are confined to the seventh row, therefore number 2 cannot appear outside of the ninth box in the seventh row. That being said, R8C8 and R9C9 can remove this digit from their candidate values. Note that only R9C9 contains number 2 as a candidate value, so we can remove number 2 from R9C9's candidate values. 

Hard Sudoku on 03/16/2018
In the seventh row all candidates of number 8 are confined to the eighth 3×3 box. Remove number 8 from R7C7 and R7C9's candidate values. 

Solve Hard Sudoku on 03/16/2018 in a stepbystep style  
Above is another example of using Interaction(a.k.a. Intersection, Locked Candidates, or Box Claim) to refine the candidate values of R7C7 and R7C9 (the highlighted squares in the seventh row excluding the eighth 3×3 box). Blank/Empty Squares are marked with candidate values in red. 

In the seventh row all candidates of number 8 are confined to the eighth 3×3 box, therefore number 8 cannot appear outside of the seventh row in the eighth box. That being said, R7C7 and R7C9 can remove number 8 from their candidate values. 

For easy understanding, in our Sudoku solver, we call InteractionBoxRow: If in a 3×3 box all candidates of a certain digit are confined to a row, that digit cannot appear outside of that box in that row. That being said, that row outside of the block can remove this digit from their candidate values. InteractionBoxCol: If in a 3×3 box all candidates of a certain digit are confined to a column, that digit cannot appear outside of that box in that row or column. That being said, that column outside of the block can remove this digit from their candidate values. InteractionRowBox: If in a row all candidates of a certain digit are confined to one 3×3 box, that candidate that be eliminated from all other squares in that 3×3 box. InteractionColBox: If in a column all candidates of a certain digit are confined to one 3×3 box, that candidate that be eliminated from all other squares in that 3×3 box. 

How to find them?





