Ah your doing the old wolf sheep cheese puzzle (was it cheese?) but i think you posted in the wrong board... I think this should be moved to the how to board....
Wolf and sheep cant stay on one side alone, cheese and sheep cant stay on one side alone and you can only carry one object on the boat...take sheep, go back, take cheese, take sheep back, take wolf, go back and get sheep voila....fun riddle though
Btw should be pretty easy just have two areas one on each sides of the shore and check wich sprites overlap that area. That way you can check if the combinations are correct...hacky but sufficient i guess...