Interactive Sudoku Solver (ISS) – Help

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Contents

Overview

The Interactive Sudoku Solver (ISS) is a solver designed to quickly solve variant sudoku puzzles. It does not use human solving techniques, instead optimizing for speed.

Use it to find all the solutions, count the solutions, or see all the valid values for each cell in a puzzle.

Visit the github repository to view the source code and report bugs.

Constraint Categories

All Constraints by Category

Recipes

Some constraint types aren't directly supported but can be constructed using combinations of available constraints.

Clone

Description: Two regions of the same shape and size, which must have the same values in corresponding cells.

Use the SameValueSets on every pair of corresponding cells to mark them as equal. Each pair must be a separate constraint.

3x3 Magic Square

Description: A square of cells, where the sum of the values in each row, column, and diagonal is the same.

Use the Cage constrain each row, column, and diagonal to sum to 15.

Odd/Even Thermo

Description: A thermometer (values are strictly increasing) where the values are either all odd or all even.

Create a Custom Binary Constraint with the following formula: 

        a < b && (a % 2 == b % 2)

Nabner Line

Description: No two digits along the line may be be consecutive. ("Nabner" is "Renban" spelled backwards.)

Create a Custom Binary Constraint with "Chain handling" set to "All pairs" and use the following formula: 

        Math.abs(a - b) > 1

Not Renban

Description: Unlike Naber, this is how to create a set where all the values taken together are not consecutive.

This requires checking that there is at least one pair of cells which have a difference of at least two, and where none of the other cells have values which are between them. Each pair can be checked with a Lockout constraint, with all the pairs inside an Or. This results in n(n-1)/2 constraints inside the Or.

Here's how you can generate the constraint (run in the browser developer console): 

        function makeNotRenban(cells) {
          const n = cells.length;
          const constraints = [];

          for (let i = 0; i < n; i++) {
            for (let j = i+1; j < n; j++) {
                const line = [...cells];
                [line[0], line[i]] = [line[i], line[0]];
                [line[n-1], line[j]] = [line[j], line[n-1]];
                constraints.push(new SudokuConstraint.Lockout(2, ...line));
            }
          }

          return new SudokuConstraint.Or(constraints);
        }

        console.log(makeNotRenban('R1C1', 'R1C2', 'R1C3').toString());