Albert Einstein's Riddle


Albert Einstein's riddle, also known as zebra puzzle, is a well-known logic puzzle. It is said that Einstein invented this puzzle when he was a boy, although there's no evidence or confirmation about his authorship. This riddle was first published by Life International magazine on December 17, 1962.

It is sometimes claimed that 98% of the world's population can't solved it. Check the Einstein's riddle below, and see if you're included in the elite 2% of intelligent people.

  1. There are five houses.
  2. The Englishman lives in the red house.
  3. The Spaniard owns the dog.
  4. Coffee is drunk in the green house.
  5. The Ukrainian drinks tea.
  6. The green house is immediately to the right of the ivory house.
  7. The Old Gold smoker owns snails.
  8. Kools are smoked in the yellow house.
  9. Milk is drunk in the middle house.
  10. The Norwegian lives in the first house.
  11. The man who smokes Chesterfields lives in the house next to the man with the fox.
  12. Kools are smoked in a house next to the house where the horse is kept.
  13. The Lucky Strike smoker drinks orange juice.
  14. The Japanese smokes Parliaments.
  15. The Norwegian lives next to the blue house.
Rules:
  • Each of the five houses is painted a different color.
  • Their inhabitants are of different national extractions, own different pets, drink different beverages and smoke different brands of American cigarets.
  • In statement 6, right means your right.

Question: Who drinks water? Who owns the zebra?


Albert Einstein

The Answer

To work this riddle, we jump first to clue (10) as it says the Norwegian lives in the first house. Then clue (15) says the Norwegian lives next to the blue house. Next clue would (9), where milk is drunk in the middle house.


Now, the next clue is a little bit hidden. We know that house 2 is blue. Therefore house 1 can't be ivory or green, since those color are next to each others, as stated in clue (6). It also can't be red, as Englishman lives there (2). So, house 1 is yellow.

Next step is easy, as clue (8) says that Kools are smoked in the yellow house, and Kools are smoked in a house next to the house where the horse is kept (12).

So what is drunk by the Norwegian in the 1st, yellow, Kools-filled house? Not tea since the Ukrainian drinks that (5). Also not coffee since that is drunk in the green house (4), nor milk since that is drunk in the 3rd house (9). Can't be orange juice since its drinker smokes Lucky Strikes (13). Therefore it is water that is drunk by the Norwegian.

So far, our table will be filled like this:



Now, comes the difficult part. We need trial and error process for the next step.

Let's start with finding what is smoked in the 2nd, blue house where we know a horse is also kept? Not Kools which are smoked in the 1st house (8). Not Old Gold since that house must have snails (7). That's leave Lucky Strike, Parliaments, and Chesterfields.

Let's suppose Lucky Strikes are smoked here, which means orange juice is drunk here (13). Then consider: Who lives here? Not the Norwegian since he lives in the 1st House (10). Not the Englishman since he lives in a red house (2). Not the Spaniard since he owns a dog (3). Not the Ukrainian since he drinks tea (4). Obviously not the Japanese too, who smokes Parliaments (14). Thus, Lucky Strikes can't be smoked in the 2nd house.

Let's suppose Parliaments are smoked here, which means the Japanese man lives here (14). Then consider: What is drunk here? Not tea since the Ukrainian drinks that (5). Not coffee since that is drunk in the green house (4). Not milk since that is drunk in the 3rd house (9). Not orange juice since the drinker of that smokes Lucky Strike (13). Again, this means that Parliaments are not smoked in the 2nd house.

So, it must be Chesterfields that are smoked in the 2nd house.

So who smokes Chesterfields and keeps a Horse in the 2nd, blue house? Not the Norwegian who lives in the 1st House (10). Not the Englishman who lives in a red house (2). Not the Spaniard who owns a dog (3). Not the Japanese who smokes Parliaments (14). Therefore, the Ukrainian lives in the 2nd House, where he drinks tea (5)!


Since Chesterfields are smoked in the 2nd house, we know from (11) that the fox is kept in either the 1st house or the 3rd house.

Let us first assume that the fox is kept in the 3rd house. Then consider: what is drunk by the man who smokes Old Golds and keeps snails (7)? We have already ruled out water and tea from the above steps. It cannot be orange juice since the drinker of that smokes Lucky Strikes (13). It cannot be milk because that is drunk in the 3rd house (9), where we have assumed a fox is kept. This leaves coffee, which we know is drunk in the green house (4).

So if the fox is kept in the 3rd house, then someone smokes Old Golds, keeps snails and drinks coffee in a green house. Who can this person be? Not the Norwegian who lives in the 1st house (10). Not the Ukrainian who drinks tea (5). Not the Englishman who lives in a red house (2). Not the Japanese who smokes Parliaments (14). Not the Spaniard who owns a dog (3).

This is impossible. So it follows that the fox is in the 1st house.

So far, we've got this result:


We're half done now. Next, where does the man who smokes Old Gold and keeps snails live? Not the orange juice house since Lucky Strike is smoked there (13).

Suppose this man lives in the coffee house. Then we have someone who smokes Old Gold, keeps snails and drinks coffee in a green (4) house. We've previously already agreed that this is an impossible situation right?

Therefore, the Old Gold smoker lives in the 3rd house with his snails.

It follows that Parliaments are smoked in the green, coffee-drinking house, by the Japanese man (14). This means the Spaniard must be the one who drinks orange juice, smokes Lucky Strikes and keeps a dog. By extension, the Englishman must live in the 3rd house, which is red. By process of elimination, the Spaniard's house is the ivory one.

The blank in the table means that the Japanese owns the zebra.

So, this is our final answer:


Tiresome, eh? Well, that's the point of hard riddles and Brain teaser. I have to admit that I'm not included in the club 2%. How about you? Did you manage to solve the above Einstein's riddle by yourself?


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