Command line sudoku solver
==========================

I was asked how I might implement a sudoku solver in a job interview and found it an interesting
problem to think about.  This is an implementation of my ideas in C.

Run "make test" to build and run the tests, "make" to build the main program.

The command accepts strings of 81 characters to specify the problem, and prints the result in the
same format.  The first 9 represent the 9 columns of the first row, and subsequent rows follow.
Each character is either a digit of 1 to 9, or a '.' to indicate unknown.