SET Solver
Find every valid set on a board of SET cards.
In the card game SET, every card has four features: a number of symbols (one, two, or three), a color (red, green, or purple), a shading (solid, striped, or open), and a shape (oval, squiggle, or diamond). Three cards make a valid set when, for each of the four features on its own, the three cards are either all the same or all different. Build the cards on your table below and the solver finds every set.
How it works
Each feature has three options, so any two cards point to exactly one third card that would complete a set with them: for each feature, if the two cards match it stays the same, and if they differ the third must be the remaining option. The solver checks every pair of cards on the table, works out the card that would complete the set, and reports it whenever that card is also on the table.
A standard layout of twelve cards usually holds a handful of sets, and can rarely hold none at all. Duplicate cards are not allowed, the same as a real deck.