Advanced sudoku generator and solver

We need C++ code to generate and solve Sudoku puzzles (no GUI code, just algorithm code required). Generator Requirements: * Must be able to generate puzzles in these sizes: 4x4, 6x6, 9x9, 12x12, 16x16 * All puzzles must have a unique solution, and be solvable using pure logic (solving techiques). * Must be able to generate the largest puzzles (16x16) within a few seconds. The user must be able to choose wether the generator should generate according to difficulty or solving technique: * Generate according to difficulties: Very Easy, Easy, Medium, Hard, Very Hard * or Generate according to solving techniques. User can check which of these that are allowed, and which are required. The allowed/required solving techniques it must be able to create puzzles out of are: Naked Single, Hidden Single, Block and Column/Row Interactions, Block/Block Interactions, Naked Subset, Hidden Subset, X-Wing, Swordfish, XY-Wing, XYZ-Wing, Colouring, Remote Pairs, XY Chains, Forcing Chains. Solver Requirements: * Must be able to determin if a puzzle is unique, how many solutions there are and return each solution. * Preferably be able to determin which solving techniques are required to solve the puzzle. Both generator and solver should be coded in C/C++ and so that we can call it from our code. The coder should have experience in a similar algorithm before starting on this project. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform C/C++, Windows.