Propositional logic SAT solvers using DPLL backward-chaining and WalkSAT
algorithms.

Usage:
$ ./DPLL -i path/to/some/input_file
$ ./walkSAT -i path/to/some/input_file -p {0..100} -f {0..N} [-H]

Where:
-p indicates the probability (percentage) to randomly choose to flip a
literal rather than choose the literal that maximizes the number of
satisfied clauses.

-f indicates the maximum number of flips WalkSAT should make before
terminating.

-H flag indicates that the program will initialize the variables using
a probabilistic heuristic.