Queens 0 of 8
Solutions found 0 of 92
Place a queen on every row, with none attacking another.
How to play
Goal
Place one queen for each row of the board (8 on the 8×8 board) so that no queen can attack another.
How a queen attacks
A chess queen attacks any distance in a straight line: along its row, its column, and both diagonals. So no two queens may share a row, a column or a diagonal.
How it works
- Tap a square to place a queen. Tap it again to remove it.
- Squares a queen attacks are lightly shaded, so you can see where the next queen can go. Turn the shading off for a harder game.
- Queens that attack each other turn red.
- Each board has several different solutions. The game counts how many different ones you have found: 10 on 5×5, 4 on 6×6, and 92 on 8×8.
Tips
- Work row by row. Place a queen in the first row, then find a safe square in the next row, and so on.
- When a row has no safe square left, move the queen in the row above to its next safe square and continue. This is called backtracking.
- Corners are rarely good starts on 8×8. Try the second or third square of the first row.
- Once you find a solution, try mirroring or rotating it. That often gives a new one.
The history of Eight Queens
German chess composer Max Bezzel set the puzzle in 1848. Mathematician Carl Friedrich Gauss worked on it, and in 1850 Franz Nauck published all 92 solutions. Today it is a classic first exercise for computer programmers.