Amongst my Christmas presents was a book, “Einstein’s riddle, paradoxes, puzzles and conundrums” by Jeremy Stangroom. One of the first puzzles in the book is this logic problem, attributed (almost certainly incorrectly) to a young Einstein:

There are 5 houses painted in 5 different colours. A person with a different nationality lives in each house. The 5 owners each drink a certain type of beverage, play a certain sport and keep a certain pet. No owners have the same pet, play the same sport or drink the same beverage.

1. The Briton lives in the red house.
2. The Swede keeps dogs as pets.
3. The Dane drinks tea.
4. The green house is immediately[1] on the left of the white house.
5. The owner of the green house drinks coffee.
6. The person who plays football rears birds.
7. The owner of the yellow house plays baseball.
8. The man living in the centre house drinks milk.
9. The Norwegian lives in the first house.
10. The man who plays volleyball lives next to the one who keeps cats.
11. The man who keeps the horse lives next to the man who plays baseball.
12. The owner who plays tennis drinks beer.
13. The German plays hockey.
14. The Norwegian lives next to the blue house.
15. The man who plays volleyball has a neighbour who drinks water.
    

Who owns the fish?

Whatever its origins, it is a cracking puzzle. It took me the best part of an hour to solve it. If your brain is under-stimulated from Christmas TV but you are forbidden from programming, I recommend you give it a go. The answer is here (no peeking!).

Normal service will be resumed on this blog soon.

[1] See Atul’s comment below.