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Shikaku solver
Stuck on a Shikaku from a newspaper, book or app? Enter its numbers below and the solver finds the answer — and tells you if the puzzle has more than one solution.
Click a cell and type a number (0–9, up to 3 digits). Use arrow keys to move, Backspace to delete.
How the Shikaku solver works
The solver lists every rectangle each number could form, then repeatedly applies the same deductions described in our strategy guide: removing options that overlap other numbers or placed rectangles, fixing numbers with one option, assigning cells that only one number can reach, and claiming cells shared by all of a number’s options. If logic alone stalls, it branches on the number with the fewest options and backtracks. It stops after finding two solutions, which is how it can tell you whether a puzzle is unique.
All solving happens in your browser — nothing is uploaded.