Patches & Shikaku Solver,
a rectangle for every clue.

Field guide

How the Patches Solver works.

Patches is a daily rectangle puzzle from LinkedIn's games, and it grew out of Shikaku, a classic Japanese logic puzzle. The board is a small grid with a few clue cells scattered across it. Your job is to divide the whole board into rectangles so that each one holds exactly one clue and matches what that clue asks for. This solver handles both the shape-hint version and the plain numbered version.

The rules the solver applies

• Every cell belongs to exactly one patch, with no gaps and no overlaps.
• Every patch contains exactly one clue cell.
• A number on a clue is the patch's area, counted in cells.
• A shape hint narrows the form: square needs equal sides, wide is wider than it is tall, tall is taller than it is wide, and any allows every rectangle. A clue with no shape behaves like any, and a clue with no number leaves its area open.

These rules follow the way the puzzle is publicly described. If a board you are looking at behaves differently, set the clue to any shape and the solver falls back to the plain Shikaku rules.

Entering your puzzle

Match the rows and columns to your board, then tap a clue cell. Type its number in the box, choose square, wide, tall or any, and the clue appears on the grid with a small outline showing its shape. Tapping a cell shows which sizes the clue could take, in rows by columns. On a keyboard you can also type digits straight into a focused cell and press S, W, T or A for the shape. The Example button loads a practice grid written for this tool.

How it finds the answer

First the solver lists every rectangle that could belong to each clue: it must contain that clue, avoid every other clue, and fit the clue's area and shape. Then it treats the board as an exact-cover puzzle and always works on the cell or clue with the fewest options left. A cell that only one rectangle can still reach is settled at once, and a dead end is spotted before any guess. A step limit protects the page from hopeless input, and the search runs in a background thread so the page never freezes.

Worked example

Take a 4×4 grid with a 4 square at row 1, column 1, a 4 tall at row 1, column 4, a 2 tall at row 2, column 3 and a 6 wide at row 4, column 1. The numbers add up to 16, the cell count. A tall 4 in a four-row grid can only be the full right-hand column. A wide 6 in a four-column grid cannot be 1 × 6, so it is 2 × 3, and the only 2 × 3 that contains the bottom-left corner fills rows 3 and 4, columns 1 to 3. The 4 square then takes the top-left 2 × 2, and the 2 tall takes what remains above the 6, rows 1 and 2 of column 3. Four clues, four patches, one answer.

Reading the result

Each patch is drawn in its own colour with its size in the corner, and the side panel lists every patch as rows by columns. Copy solution puts a lettered grid and the list on your clipboard. Below the list you will see whether the split is the only one that fits. If it is not, the clues are probably misread.

Tips for solving Patches yourself

• Start with the tightest clue. A 9 square can only be 3 × 3, and a tall 5 in a five-row grid can only be one full column.
• Look for cells only one clue can reach. If a cell is out of range of every clue but one, that clue's patch must cover it.
• Check the total. If every clue has a number, they must add up to the cell count. A mismatch means one was misread.

Disclaimer: This tool is an independent fan creation and is not affiliated with, authorized, or endorsed by LinkedIn Corporation. “Patches” is a trademark of its respective owner, and Shikaku is the name of a long-established Japanese puzzle. Provided for practice and entertainment only.