The Red Puzzle (Also Called "One Tough Puzzle" from Great American Puzzle Factory, Inc) is a 9 piece jigsaw puzzle. It is very hard because every piece has four nubs. There are no edge pieces. There are over 300,000 incorrect configurations. The brute force solver will solve it in about 5,000 - 60,000 iterations. It shuffles the pieces so there is a different result each time. The search algorithm tries pieces until it finds one that doesnt fit. If none of the remaining pieces fit after all rotations have been tried, it backtracks one position and tries again. Its guaranteed to find a solution if there is one. Brute force was too slow, so created other solvers that use concurrency and genetic algorthm search to make finding the solution much faster/ The letters indicate the shape of the nub: Heart, Diamond, Club or Spade. Maybe someday I will draw the pieces as they really look.