Logic Masters Deutschland e.V.

Place the digits 1 to 9 once each into every row, column and region. Regions must be discovered by the solver.

All question mark clues have unique values - a '?' indicates a single-digit value, while a '??' indicates a double-digit value.

The value of a question mark clue is equal to the sum of the first 'X' digits seen in that row/column, where 'X' is the first digit seen. These cells must all belong to the same region, and a separate region must exist directly after these cells (or the edge of the grid).

A red clue indicates that the next region also follows these rules, and must sum to the same total. For example, if R9C2 was a 3 and the 3 digits seen summed to 18, then the next region seen might start with a 4, and the 4 digits seen within that region would also sum to 18.

An arrow in a grid cell indicates that 'Y' distinct regions can be seen in that direction from that cell, where 'Y' is the cell value. The arrow does not count its own cell, but does count its own region if the region can be seen beyond the arrow cell. Not all arrows are necessarily given.

The '<' points to the smaller digit of the two cells.

The sum of the digits along each main diagonal (indicated by the bold arrows) must be the same.

Solve on SudokuPad