Handle cube file stored in a sub-directory for `solve-single-cube.sh`

[piyush-J]

We get an error if we have the cube file stored in the sub-directory, e.g., in the snippet given below, 4.cubes is stored in 19-files/19-cubes:

./solve-single-cube.sh 19 constraints_19_c_100000_2_2_0_final.simp 19-files/19-cubes/4.cubes

The current hack is to move 4.cubes into the main directory and use:

./solve-single-cube.sh 19 constraints_19_c_100000_2_2_0_final.simp 4.cubes

[BrianLi009]

Issue is resolved. I've tested the new script and the following command should work now: ./solve-single-cube.sh 19 constraints_19_c_100000_2_2_0_final.simp 19-files/19-cubes/4.cubes 1