The puzzle of the goat, the wolf and the hay - solution

Have a go at the problem, and it may seem impossible. However, if you take it a step at a time, you should be able to work out a solution.

Don't worry about who eats who! The important point is that the wolf and the goat must not be left alone, and neither must the goat and the hay. So the only allowable pairing is the wolf and the hay. Wolves don't eat hay!

So the start is easy. You have to take the goat across and leave the wolf and hay alone. Any other first step finished the game immediately. Leave the goat on the other bank, and come back with an empty boat.

It doesn't matter whether you take the wolf or hay across next. Let's say that you choose the wolf. Once the wolf has crossed and gone onto the bank, there are the goat and wolf together. You can't leave them there and return with an empty boat, as the wolf will eat the goat. However, you CAN bring something back. (The hint tells you that you can do this.) There's no point in taking the wolf back, as you've just brought it across. So obviously, you have to take the goat back.

Now you have a choice of taking the goat or hay back. There's no point in returning the goat; you've only just brought it back. Try the hay.

Now the wolf and hay are on the far bank. Hooray! They can be left alone. Return with an empty boat, and collect the goat. There you are, all three across!

There are two things to learn from this problem. First, if a problem seems impossible, there may be another way of looking at things or a sly way of doing things that doesn't occur to you at first. You have to take these three animals across the river, so you only think of taking them one way. Bringing one back just seems to go backwards. But that is the only way to solve the problem. If a problem seems impossible to solve sensibly, then try thinking of odd things. This is sometimes called lateral thinking. The second point is that if you actually try to take the animals across, at any point there is not really a true choice of things to do. You seem to have a choice, but either you undo what you have just done (take the wolf across and then bring it back again - really not helpful!), or you do something that immediately causes trouble (leaving the wolf and goat together, or goat and hay together), or the choice is irrelevant (at one point you can choose wolf or hay - it's irrelevant), or it's the only remaining choice, and that one is the one you should take. Try and do it, and think about each choice, one step at a time. Sometimes a complete puzzle is too complicated, but each step is solvable.

Some smart alec may point out a better solution, tether the goat so it can't reach the hay and muzzle the wolf. Yes, yes. You're quite right. In the real world the solutions tend to be practical rather than logical. But this is a logic puzzle. After all, what are you doing with a wolf, anyway!