River crossing puzzle

Asked Feb 27 '17 at 00:12

Active Feb 27 '17 at 00:14

Viewed 1,048 times

I was thinking about implementing the classical river crossing puzzle game and I was wondering what would be the most appropriate search algorithm to solve it. Here is an example of the game

Apparently there is enough information to predict the distance from the current state to the goal, so a heuristic search could be used. Going through the different states I found a case where the search can enter an endless loop. Here is the case: On the left side of the river there are two creatures (one of both kinds) On the right side of the river there are four creatures (two of both kinds) The boat is on the right side

There are 2 legal moves:

return two munchkins (those who should not be outnumbered by the others) this will cause a loop
return two creatures (1 of both kinds) this is the move that should be taken

Is the usage of informed search better in this case? What would be the appropriate type of heuristic i.e Hill Climbing, A* What would be the best way to go through that looping.

edited Feb 27 '17 at 00:14

lejlot

64,777
8
131
164

asked Feb 27 '17 at 00:12

Jason Per

1

just memorize states you have visited (hash-based set) and you can use any search method you like. – lejlot Feb 27 '17 at 00:15
@lejlot I am looking for a memory and time efficient search method this would probably be a heuristic one. How would the hashset prevent the looping.Could you please clarify your answer ? – Jason Per Feb 27 '17 at 00:17
1

if you keep a container with info which states have been visited (hash set) then you simply never go to the state you have been before - thus no looping possible. – lejlot Feb 27 '17 at 00:25
@lejlot This makes sense ! – Jason Per Feb 27 '17 at 00:28
Are you looking for the optimal solution? – César Rodríguez Apr 03 '17 at 11:14

River crossing puzzle

0 Answers0