Backtracking Animation
a 12-A puzzle — see instructions below.
Card Pool
Game Board
The card pool initially contains 9 cards arranged to display 12 two-color letters “A.”
Goal of the puzzle: Place the 9 cards on the game board so that 12 single-color letters “A” are visible *).
Moving the cards:
- Tap or click a card in the card pool: The card moves from that slot to the first empty position on the game board.
- Briefly tap or click a card on the game board: The card rotates one quarter turn counterclockwise.
- Press and hold a card on the game board for about 0.6 seconds: It returns to its original slot in the card pool and to its starting orientation. Alternatively, tap or click the number of its slot in the card pool below.
The puzzle always starts in “manual” mode. As soon as “auto” is selected, an automatic “backtracking” algorithm takes over the search for a solution; it can be interrupted at any time by switching to “manual.” The algorithm runs at an adjustable speed and stops when it finds a solution. You can then select “continue” or switch to “manual” and back to “auto” to search for additional solutions.
The “reset” button starts a new game with a different starting arrangement in the card pool.
*) Whenever possible, display a solution for the first time in “manual” mode (you will be rewarded!).