PuzzleSolver

This is a backtracking framework with rules. It works by constructing a solutions tree of Partial solutions. Each partial solution in the tree has rules applied to it until no more rules apply or until some rule indicates that it cannot lead to a solution. Once all rules have been applied and the node hasn't been ruled out by any of them, the successor nodes in the backtracking tree are created. Any duplicate nodes are pruned from the tree and the process repeats until we've found a solution. The nodes can be ordered according to some heuristic if desired. I've used this to both create and solve Battleship type puzzles, sudoku and alphametics. It uses very general interfaces so it can be easily adopted to almost any such sort of puzzle.