Queens solver: we put the dodos to bed for you

How to use it

1. Take a screenshot of your grid, ideally before placing any crowns: an empty grid reads better. Tap “Read a screenshot”, or paste it straight in (Ctrl+V).
2. Check the colours. If a square was misread, pick the right swatch and repaint it. There are as many gardens as rows, and the solver tells you if one is missing.
3. Ask for a hint. A single deduction, shown on the grid: the squares involved light up, the ones ruled out get a red cross. Press again for the next one.
4. Or surrender with dignity: “The whole solution” puts every dodo to bed at once. Nobody will know, apart from you and the dodo.

What it tells you besides the answer

Most solvers hand you the answer and stop there. This one replays the grid like a player would: it only uses the game’s six deductions, and never tries a square “just to see”. Hence three possible verdicts.

• One solution, no guessing. The grid is honest. The solver even names the finest deduction it needs.
• One solution, but the deductions stall. At some point you have to try a dodo and see whether everything holds. It is not you, it is the grid.
• Several solutions, or none. A real Queens grid has exactly one. Most of the time it is a misread colour: repaint the guilty square.

The six deductions it uses

They are exactly the ones that check every Dodoku level before it reaches you, and the ones the hint names:

• The last free square: a row, a column or a garden has one square left, the dodo goes there.
• The garden that fits in one row: its dodo will be there, the rest of the row is ruled out.
• The row that fits in one garden: the reverse, the rest of the garden is ruled out.
• The square that would empty a garden: a dodo there would touch every free square of a small garden.
• Gardens shut inside as many rows: two gardens in two rows, those rows belong to them.
• Rows that only cross as many gardens: the same reasoning, the other way round.

The Queens puzzle rules guide walks through them one by one, with diagrams and the method for never guessing.

What it does not do (yet)

It reads screenshots, not photos of a screen taken at an angle, nor printed grids. In those cases, colour it by hand: an 8 × 8 grid takes a minute, dragging your finger from square to square.

It ignores crowns already placed on your screenshot and starts again from the empty grid. To find out where you went wrong, compare your grid with the solution.

Frequently asked questions