Einstein's Challenge

The easiest way to solve this puzzle is start with a grid and begin filling it in with clues. Clues 8 and 9 allow us to fill in cells directly:

Clue 14 places the blue house next to the Norwegian, and the green and white houses as 4 and 5 (not 3 and 4 because clue 5 has the green house owner drinking coffee).

Clue 1 says that the Brit lives in a red house, which rules out all but 3. By process of elimination, the first house is yellow. Clue 7 adds to this the fact that the owner smokes Dunhills.

Clue 11 places horses next to the Dunhill house. The beer drinker smoke Blue Master, the Dane drinks tea, and Milk and Coffee are in houses 3 and 4. So the Norwegian, who smokes Dunhill, drinks water. And the water drinker's neighbor smokes blend. With the only beverages remaining being tea and beer, and knowing that the beer drinker smokes Blue Master, the second house has the tea drinking Dane.

The last beverage, beer, goes in house 5 with it's Blue Masters. The German Prince-smoker must therefore be in House 4. This leaves the Swedish dog owner for House 5, then the bird-rearing Pall Mall smoker for House 3.

Since the cat owner lived next the Blend smoker, we can see that there is only one slot left, in the German's house. So it is the German who keeps the fish.

And for the bonus, could Einstein have created this puzzle as written here at the end of the 19th century? While Einstein was a young man, he certainly could have posed some sort of puzzle similiar to this one. But we know definitively that he could not have presented as it is here in the 19th century, because of the cigarette brands. Alfred Dunhill didn't open up a tobacco shop until the early 20th century. Blue Masters weren't launched until 1937. Pall Mall cigarettes weren't introduced until 1939.