This simple logic puzzle will challenge the versatility of the solver. Invented by Trevor Truran, he said he’d be hard pushed to think up another puzzle where you need the clues that are not there just as much as the ones that are.
In the grid, signs have been placed in all occurrences of where a digit must be plus one (+) or minus one (–) from the digit next to it. It’s the logical negative of this rule that makes for an interesting puzzle.
Sudoku, Irregular Sudoku and Killer Sudoku versions of this puzzle are also available.
Each line across and down must contain all the digits from 1 to x (x being the number of cells in a row). Reading from left to right or top to bottom, a sign between two digits indicates if it is plus one (+) or minus one (–) from the digit next to it. Signs are applied to all occurrences of this rule.
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