Five Houses Puzzle

Who owns the fish?

Here are fifteen clues:

This is an example of what we might call “multiple-attribute” puzzles. Here we have a five-by-five challenge:

five colours
five nationalities
five drinks
five cigars
five pets.

The solution is arrived at by using a combination of logic and trial-and-error, mainly logic. Many of the clues are interdependent, which makes solving the puzzle confusing at first.

Nevertheless, the puzzle cannot be solved without relying on this interdependence.

The first thing towards finding a solution should be to draw a picture of the street, calling the houses A, B, C, D and E, with the Colour, Nationality, Drink, Cigar and Pet attributes running vertically, in that order.

Next, we fill in any obvious items, as follows,

From Clue 9, we can place the Norwegian in house A,
from Clue 14, we can colour house B Blue,
from Clue 8, we can place the Milk drinker in house C:

Now, looking at Clue 4, we try to locate the Green and White houses. They can’t be either (A — B) or (B — C), because B is Blue.

Nor can Green and White be (C — D). Why? Because Clue 5 puts the Coffee drinker in the Green house and house C has a Milk drinker. It follows that the Green house is D and the White is E.

This leaves us to find the Colour of houses A and C.

Because Clue 1 puts the Brit in the Red house, and House A has a Norwegian, we can deduce that House C is Red and House A is Yellow.

And while we’re at it, we can place the Dunhill smoker in his house (Clue 7), the Brit in his (Clue 1), the Coffee drinker in his (Clue 5) and the Horse owner in his (Clue 11):

We are now over 40% done, but from here on it gets a little more difficult.

Let’s try to place the other drinks — Beer, Water and Tea.

Taking house A, it can’t be Tea drunk here because the Tea drinker isn't Norwegian but Danish (Clue 2). Likewise, it can’t be Beer in house A because the beer drinker smokes Blue Masters (Clue 12) whereas the Norwegian in house A smokes Dunhill. House A must therefore have the Water drinker.

From this and Clue 15 it follows that the Blends smoker lives in house B.

Now, what is the nationality of the owner of house B?

Either German, Swedish or Danish. But he can’t be German (Prince smoker, from Clue 13), since house B’s owner smokes Blends. Nor can he be Swedish (Dog owner, from Clue 2), since house B’s owner keeps a horse. So house B must be the Dane’s, who from Clue 3 is the Tea drinker.

The Beer drinker (and Blue Masters smoker, from Clue 12) must therefore live in house E. This cannot be the German, from Clue 13, and thus has to be the Dog owning Swede (Clue 2), leaving house D’s owner as the Prince smoking German.

This means that the Brit in house C must smoke Pall Mall and is therefore the Bird fancier (Clue 6):

Finally, Clue 10 reveals that the next-door neighbour of the Blends smoker who keeps cats must live in house A.