Basic WalkSAT version.
Variables are chosen among candidates in only ONE top level assertion with MINIMAL top_score.
No restarts.

#define _CNF_ 0
#define _BFS_ 2
#define _FOCUS_ 1
#define _RESTARTS_ 0
#define _TIMELIMIT_ 300
#define _SCORE_AND_AVG_ 0
#define _SCORE_OR_MUL_ 0