This is a Melon puzzle. (23 – Sudoku +/- 4)
or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Number entry mode and a shading mode to help track complete clues.)
Theme: Clue Symmetry, and Very Hard WPC Practice
Rules: Variation of Sudoku. Place integers from -4 to 4 into each cell so that each row, column, and region contains each integer from -4 to 4 exactly once. The numbers outside the grid represent the sum of all integers between that clue and the zero in that row/column. Some cells inside the grid already contain an integer but no sign is given. It is part of the puzzle to determine if these values are positive or negative. An example using -2 to 2 from the WPC instructions is here.
Answer String: Enter the numbers (ignoring sign) from left to right in the marked rows, separating each row with a comma (eg “123401234,431023412”).
Time Standards (highlight to view): Grandmaster = 10:00, Master = 16:00, Expert = 32:00
Solution: PDF