Check if a puzzle is solvable
If the clue sum matches the board area, the solver can test whether at least one full rectangle partition exists.
Solver
Shikaku Solver
Interactive
6 x 6
Choose a size, click a cell, add clues, then use Check & Solve.
Selected cell: none
Clue sum
0 / 36
Solutions
0
Uniqueness
Not checked
Showing
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What This Shikaku Solver Does
This tool lets you enter any Shikaku board by clue positions and clue values, then checks whether the puzzle can be partitioned into valid rectangles. It is built for players who want help on a stuck puzzle and for puzzle authors who want a fast validity check before publishing a board.
Unlike a simple answer viewer, this solver enumerates legal rectangles for each clue and then searches for a full, non-overlapping covering of the board.
When the Solver Helps
Test custom clue layouts
You can enter your own clue positions and values, then check whether the full board can be partitioned into legal rectangles.
Review multiple solutions
If a board is not unique, you can cycle through the first few solutions and compare how the partitions differ.
Frequently Asked Questions
Does every Shikaku puzzle have a unique solution?
No. A puzzle can have one valid rectangle partition, multiple valid partitions, or no valid partition at all if the clues are inconsistent.
Why does the clue sum need to match the board area?
Each clue is the area of exactly one rectangle. If the total clue area does not equal the board area, the board cannot be fully covered.
Can I use custom board sizes?
Yes. The solver highlights four common sizes first, but you can open Custom and enter a different width and height when needed.
Will this page connect to backend APIs later?
Yes. The page is designed so puzzle validation, hint generation, analytics, and archive lookups can later move to backend endpoints without changing the page structure.