Logic Masters Deutschland e.V.

Inspired by an idea by The Book Wyrm and a suggestion by Myxo.

Rules

Place the digits from 1 to 9 and a blank cell exactly once in every row and column.

Draw three loops that travel orthogonally between the centres of some cells in the grid. The loops may NOT cross themselves and MAY cross each other, but wherever they cross, both ends must travel straight; a cross is never two right angles touching; in any other case the loops may not overlap. The loops may NOT travel through blank cells.

One of the loops is a Negator loop, a digit X on the loop is modified to have the value -X.

Clues to the left of rows indicate the sum of values on horizontal segments of the loops in that row, in the correct order. Clues above columns indicate the sum of values on vertical segments of the loops in that column, in the correct order.

In each row and column either all clues or no clues have been given. All minus signs have been removed from the clues.

The negative digits also affect the other regular loop sums. ... can represent any number of sums, including none. A ? can be any digit 0-9.

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Penpa

Sudokupad