A Sudoku solver using recursive backtracking in Java.

Takes a plain-text file containing the unsolved puzzle in matrix form,
with 0's for the unknowns. The example provided is from http://www.websudoku.com,
and an evil one. The program can solve it, provided you run it with a 
stack size of about 50m. For simpler Sudoku's, you will not need this big
of a stack size.

Note: you need to change the path to the sudoku.txt file in the code to point
to your sudoku.txt file. Then compile, and then run, preferably with a 
'-Xss50m' option, to allocate a stack size of 50m.

~Signed
AmbidextrousTx
Dec 20, 2010