1 Sudoku Solver

We’ll implement Sudoku solvers and generators, including an HTTP-based protocol for obtaining generated boards.

1.1 Solver and Generator

Due date: by January 21

Implement a Sudoku solver. Your solver should at least work on 3×3 boards (i.e., 81 cells), but ideally it should work on an arbitrary M×N boards.

Also, implement a Sudoku board generator. The generator should generate a random board. (It should ideally be able to generate any possible Sudoku board that has a unique solution, but it’s not clear to the instructor that such a general generator is feasible.)

For the solver and generator part of the assignment, no particular input or output is required.

For the general M×N case, M and N do not have to be unique. An example solved 1x2 board is

and an example solved 3x2 board is

1.2 Client and Server

Due date: by January 28

Create client and server wrappers for your Sudoku solver.

The client should take a URL and download a board from that site, where the URL will always end in ".txt" and the protocol is HTTP 1.0. The server should provide a board via HTTP 1.0 as unencoded ASCII.

A served board is a sequence of numbers (composed of digits 0 through 9) and _, where any amount of whitespace (space, newline, carriage return, or tab) separate the numbers and _ tokens. The first two items represent the board dimensions M and N, and the rest of the items represent the board content, from left to right and then top to bottom, where _ represents an empty cell. Non-blank cells have numbers from 1 to M×N (inclusive).

For example, a Sudoku-board server might return the following content: