Riddle of the Week

Riddle of the Week: Einstein's Riddle

Difficulty level: Hard

Michael Stillwell
 
By Jay Bennett

Legend has it that Einstein wrote this riddle when he was still a young man. Some claim that he would give these puzzles to students so they would be dissuaded from choosing him as an academic advisor, but as Stanford notes, "it is not likely that there is any truth to these stories."

Regardless, the problem has become known as Einstein's Riddle. They say only 2 percent of the population can solve it, but I do not believe such claims, and I will tell you this: if you are well versed in Sudoku, then you should have no problem at all.

PROBLEM

There are five houses sitting next to each other on a neighborhood street, as depicted in the picture above. Each house's owner is of a different nationality. Each house has different colored walls. Each house's owner drinks their own specific beverage, smokes their own brand of cigar, and keeps a certain type of pet. None of the houses share any of these variables—nationality, wall color, beverage, cigar, and pet—they are all unique.

Here is what you know:

1. The Englishman lives in the house with red walls.
2. The Swede keeps dogs.
3. The Dane drinks tea.
4. The house with green walls is just to the left of the house with white walls.
5. The owner of the house with green walls drinks coffee.
6. The man who smokes Pall Mall keeps birds.
7. The owner of the house with yellow walls smokes Dunhills.
8. The man in the center house drinks milk.
9. The Norwegian lives in the first house.
10. The Blend smoker has a neighbor who keeps cats.
11. The man who smokes Blue Masters drinks beer.
12. The man who keeps horses lives next to the Dunhill smoker.
13. The German smokes Prince.
14. The Norwegian lives next to the house with blue walls.
15. The Blend smoker has a neighbor who drinks water.

The question is this: One of the house owners keeps fish, who is it?

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