This program used DLX to solve sudoku
Because of Makefile, can compile by using "make" command
There are 3 test files :
test0.in : no solution
testH.in : only one solution
testW.in : more than one solution
Can use "<" to input file into program
ex:
./solve_DLX.exe < testH.in
Can use "time" to check time-consuming
ex:
time ./solve_DLX.exe < testH.in