-
- add234(possibilities, new_xyd(state->cx, state->cy, R));
- add234(possibilities, new_xyd(state->cx, state->cy, U));
- add234(possibilities, new_xyd(state->cx, state->cy, L));
- add234(possibilities, new_xyd(state->cx, state->cy, D));
+
+ if (state->cx+1 < state->width)
+ add234(possibilities, new_xyd(state->cx, state->cy, R));
+ if (state->cy-1 >= 0)
+ add234(possibilities, new_xyd(state->cx, state->cy, U));
+ if (state->cx-1 >= 0)
+ add234(possibilities, new_xyd(state->cx, state->cy, L));
+ if (state->cy+1 < state->height)
+ add234(possibilities, new_xyd(state->cx, state->cy, D));