End the War on Freedom

Einstien supposedly created the following puzzle:

There are 5 houses in 5 different colours. In each house lives a person of a different nationality. The 5 owners drink a certain type of beverage, smoke a certain brand of cigar, and keep a certain pet. Using the clues below can you determine who owns the fish?

• The Brit lives in a red house.
• The Swede keeps dogs as pets.
• The Dane drinks tea.
• The green house is on the immediate left of the white house.
• The green house owner drinks coffee.
• The person who smokes Pall Mall rears birds.
• The owner of the yellow house smokes Dunhill.
• The man living in the house right in the middle drinks milk.
• The Norwegian lives in the first house.
• The man who smokes Blend lives next door to the one who keeps cats.
• The man who keeps horses lives next door to the man who smokes Dunhill.
• The owner who smokes Blue Master drinks beer.
• The German smokes Prince.
• The Norwegian lives next to the blue house.
• The man who smokes Blend has a neighbour who drinks water.

Here's my solution. Stop reading now if you want to work it out yourself.

First off, it's necessary to assume that the "first house", in which the Norwegian lives, is on the far left. I haven't worked it out if you assume that it's on the far right.

Since the green house owner drinks coffee, the green house cannot be in the middle, as its owner drinks milk.

The second house is blue, hence, since the green house is on the immediate left of the white house, it must be in position 4 (counted from the left). Since the brit lives in the red house, the Norwegian must live in the yellow house. This means that the houses are in the following order, with known relationships in parentheses:

yellow (Norwegian, Dunhill), blue (horses), red (Brit, milk), green (coffee), white

And here are the remaining clues, shortened for ease off use, and organized as smoke, pet, drink, and nationality:

• Pall Mall, birds
• Blend next to cats and next to water
• Blue Master, beer
• Prince German

• cats next to Blend
• dogs Swede
• fish

• tea Dane
• water next to Blend
• beer next to Blue Master

• German Prince
• Swede dogs
• Dane tea

Since the Blue Master smoker drinks beer, he must live in either the blue or white house. Assume he lives in the blue house. Then Blend is in the green house (it can't be next to water in the red or white), the Prince-smoking German is in the white house with his water, and the Brit smokes Pall Mall:

  yellow (Norwegian, Dunhill), blue (Blue Master, beer, horses), red (Brit, Pall Mall, milk, birds), green (Blend, coffee), white (German, Prince, water, cats)

Now the Swede and his dogs must go in the green house, so there's no place for the Dane with his tea. Our Blue Master assumption must have been incorrect.

Backing up, The Blue Master smoker must be in the white house with his beer:

  yellow (Norwegian, Dunhill), blue(horses), red(Brit, milk), green (coffee), white (Blue Master, beer)

Now Blend has to be either in the blue or red house (it can't be next to water in green or white). Assume its in the red house. Then water is drunk in the blue house, cats are kept in the green house, the Swede keeps his dogs in the white house, and once again there's no place for the Dane and his tea.

So, back up once again. Blend must be smoked in the blue house, the Norwegian drinks water, the Dane must live in the blue house with his tea, and the German must smoke his Prince in the green house.

yellow(Norwegian, Dunhill, water), blue(Dane, Blend, tea, horses), red(Brit, milk), green (German, Prince, coffee), white(Blue Master, beer)

The remaining unused clues are:

• Pall Mall, birds
• Blend next door to cats
• Swede, dogs

So the Brit must smoke Pall Mall and keep birds, the Norwegian must keep cats, and the Swede must live in the white house with his dogs:

  yellow (Norwegian, Dunhill, water, cats), blue (Dane, Blend, tea, horses), red (Brit, Pall Mall, milk, birds), green (German, Prince, coffee), white (Swede, Blue Master, beer, dogs)

Conclusion: the German owns the fish.