Logic Masters Deutschland e.V.

Normal 4x4 Sodoku Rules Apply

Place the digits 1–4 in the grid so that each digit appears exactly once in every row, every column, and every 2×2 box.

Hidden Killer Cages

The entire grid must be partitioned into hidden Killer cages satisfying all of the following:

• Every cell belongs to exactly one cage.
• Each cage is orthogonally connected.
• DIGITS may not repeat within a cage.
• Single-cell cages are allowed.
• Cage boundaries and cage sums are not given and must be determined by the solver.

DIGITS and VALUES

Each cell has two numerical attributes:

• The DIGIT of a cell is the ordinary Sudoku digit placed in that cell.
• The VALUE of a cell is the sum of the DIGITS in the Killer cage containing that cell.

Thus, all cells belonging to the same Killer cage have the same VALUE. For example, if a cage contains the DIGITS 1 and 3, then both cells in that cage have VALUE 4.

Different Killer cages may have the same VALUE.

Corner Restriction

None of the four corner cells may have VALUE 6.

MOD-VALUE

Each cell also has a MOD-VALUE, obtained from its VALUE modulo 4 and represented using the numbers 1–4:

• VALUES congruent to 1 modulo 4 have MOD-VALUE 1.
• VALUES congruent to 2 modulo 4 have MOD-VALUE 2.
• VALUES congruent to 3 modulo 4 have MOD-VALUE 3.
• VALUES congruent to 0 modulo 4 have MOD-VALUE 4.

For example, VALUES 5, 6, 7, and 8 have MOD-VALUES 1, 2, 3, and 4 respectively.

Negative Row and Column Indexing

Rows are numbered 1–4 from top to bottom, and columns are numbered 1–4 from left to right.

For every cell:

• its MOD-VALUE must not equal its row number; and
• its MOD-VALUE must not equal its column number.

Negative Box-Position Indexing

Within each 2×2 box, the four cell positions are indexed as follows:

1 2
3 4

For every cell, its MOD-VALUE must not equal its position index within its 2×2 box.

SudokuPad Link