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Garrett Hoofman ..:: visions of afar ::..

Today I saw this puzzle on the Internet. I love puzzles like these, which is probably why I like to program so much. It took me about 30 minutes and a couple sheets of paper to rifle through it all and get the answer.

How fast can you guys get it? Comment, and I'll let you know if you're right or not.

### Einstein's Logic Puzzle

So you want a hard brain teaser! Well, here it is.

It's purported that Einstein said 98% of the world's population could not figure out this logic problem. Try your hand at it.

A logical question.

There are 5 houses each with a different color. Their owners, each with a unique heritage, drinks a certain type of beverage, smokes a certain brand of cigarette, and keep a certain variety of pet. None of the owners have the same pet, smoke the same brand of cigarette or drink the same beverage.

Clues:

• The Brit lives in the red house.
• The Swede keeps dogs as pets.
• The Dane drinks tea.
• The green house is just to the left of the white house.
• The green house's owner drinks coffee.
• The person who smokes Pall Malls raises birds.
• The owner of the yellow house smokes Dunhill.
• The man living in the center house drinks milk.
• The Norwegian lives in the first house.
• The man who smokes Blends lives next to the one who keeps cats.
• The man who keeps a horse lives next to the man who smokes Dunhill.
• The owner who smokes Bluemasters also drinks beer.
• The German smokes Prince.
• The Norwegian lives next to the blue house.
• The man who smokes Blends has a neighbor who drinks water.

Who owns the fish?

Posted on Tuesday, December 18, 2007 2:50 PM | Back to top

Comments on this post: Einstein's Puzzle

# re: Einstein's Puzzle
What fish?
Left by Thomas Williams on Dec 18, 2007 4:30 PM

# re: Einstein's Puzzle
German - about 20 minutes, but I used excel to layout who lives where.
Left by John Workman on Dec 18, 2007 11:11 PM

# re: Einstein's Puzzle
German again. Also used Excel. Took about half an hour, with a moderate skinful, late at night. Not too shabby all things considered.

Mein Herr also lives in tte green house, fourth from the left, likes coffee and smokes Prince.

I've been meaning to solve this one for years, nice to have got the monkey off my back at last.
Left by Yehudi on Dec 28, 2007 8:08 AM

# re: Einstein's Puzzle
Using Exel is point blanck chitting, because it is very easy. Try to use your brain. Because the whole idea of the puzzle is to test the short term memory, deductive, inductive and reductive thinking. Exel will do it just by going through all the possibilities fast... very fast, which would take you years. Hate to pop your buble! Vik
Left by Viktor on Mar 21, 2008 8:07 PM

# re: Einstein's Puzzle
German 20 mins pencil and paper. only 13. what.then.
Left by laura on Jun 25, 2008 12:29 AM

# re: Einstein's Puzzle
im only 13 is what i meant. i didnt cheat, by the way
Left by laura on Jun 25, 2008 12:33 AM

# re: Einstein's Puzzle
i used excel.....it tooked me one hour to complete it......it is very hard to analyze....but i am proud that i am in the 2% that can solve it
Left by eyvid on Aug 12, 2008 7:33 AM

# re: Einstein's Puzzle
German, 16 min 9.69 sec to be exact
Left by Adam on Aug 21, 2008 11:22 AM

# re: Einstein's Puzzle
Anyone who did this on Excel cheated. You've got to do it with pencil and paper only as Einstein devised it before everyone had computers. I managed it properly, I'm glad to say.
Left by Tim on Sep 21, 2008 12:33 PM

# re: Einstein's Puzzle
I would like to state, that in today's society, the 2% rule is complete bull(bad word) we did this in class one year, and almost everyone got it. I did it in about 20-30 minutes. today we are much better educated, and nearly any Child in the schooling system, and any adult can do this.
Left by Hans on Oct 22, 2008 2:05 AM

# re: Einstein's Puzzle
Einstein wasn't that smart. In under a minute I discovered at least two logical gaps that prevent a solution to this problem:

1. It is not clear that anyone owns a fish. One "clue" must be "someone owns a fish". Without this, the problem has no solution

2. It is not clear what the arrangement of the houses are. Perhaps they are in a circle, or 2 are across the street from the other 3.

So the answer is clear. This problem has no solution.
Left by Rip Rowan on Nov 12, 2008 10:21 AM

# re: Einstein's Puzzle
I used Excel as well but I used it like I would pencil and paper. First you put down the facts, established colors, pets, nationalities, drink, cigerettes each in it's own category.

Then what the teaser told you who was where.

You put the separate facts that fit together.

Then bam!

Took me about 20 mins (sorry im a slow poke :P)

The meticulous or genius will get this. Some people like me need visual representation to solve (which isn't a detractor for intelligence in my opinion). It didn't say how you could do it. Cheating would be putting the whole phrase into google and finding the answer before solving it.
Left by Marc on Dec 01, 2008 11:37 PM

# re: Einstein's Puzzle
It took me about an hour. I was watching TV mostly and solving the puzzle at the commercial breaks. I still prefer using pen and paper. (I think) it is the better to analyse the puzzle with your brain rather let computer do the job.
Left by JT on Dec 10, 2008 11:24 AM

# re: Einstein's Puzzle
The reason that only 1% of the population would be able to solve this puzzle, is that only that one percent can solve it in their head, with out the pencil & paper, or the excel.
I can only dream of being able to keep track of that many things in my head all at once, and then try to use it to solve a question. Yikes.
Left by Garrett Hoofman on Dec 10, 2008 11:44 AM

# re: Einstein's Puzzle
i was given it by one of my friend Haris, I Solved it in 15 miunutes, using a paper and a pencil. It simple logic...
Left by miuks on Jan 10, 2009 3:58 AM

# re: Einstein's Puzzle
German lives in green house he drinks coffee Prince-smoking and he has the fish.
Left by Fatonnn on Feb 11, 2009 12:57 PM

# re: Einstein's Puzzle
yups......

98% people answer German....

2% people Norwegian
Left by psychopast on Feb 18, 2009 9:54 PM

# re: Einstein's Puzzle
I solved in 15 min it was it needed good concentration I will say making a puzzle is very hard rather than solving so don't go on top of the world and the answer is the germans owned the fishes
Left by Soumik on Mar 01, 2009 3:06 AM

# re: Einstein's Puzzle
45 mins, used pen and paper, and my brain

came to the concl;usion that the German has a fish
Left by Liam on Apr 03, 2009 4:26 AM

# re: Einstein's Puzzle
17 years old. 10 minutes is my guess, i didnt time it, but that's more than likely an overestimation. Much easier than I anticipated. Pencil/paper
Left by bored on Apr 18, 2009 3:13 PM

# re: Einstein's Puzzle
oh yeah, to agree with a comment above, some of the instructions are a bit lacking. the one that bothered me the most was "The Norwegian lives in the first house." What defines "the first house?"
Left by bored on Apr 18, 2009 3:16 PM

# re: Einstein's Puzzle
To solve Einstein's puzzle, we represent each of the fifteen constraints as a regular language and intersect these languages with the initial set of all possibilities. If all goes well, at the end we will know who keeps fish. For example, we can interpret The Englishman lives in the red house. as \$[red Englishman]. This constraint is trivial to encode because in our representation of a house, the color and the nationality are adjacent. The second costraint, The Swede keeps dogs could be represented as \$[Swede Drink Cigarette dogs] but we will choose a less verbose formulation, \$[Swede ~\$Pet dogs], that does not explicitly list the variables that separate Nationality and Pet. The fifteen constraints are shown below.

define C1 \$[red Englishman];
# The Englishman lives in the red house.
define C2 \$[Swede ~\$Pet dogs];
# The Swede keeps dogs.
define C3 \$[Dane tea];
# The Dane drinks tea.
define C4 \$[green ~\$Color white];
# The green house is just to the left of the white one.
define C5 \$[green ~\$Drink coffee];
# The owner of the green house drinks coffee.
define C6 \$[PallMall birds];
# The Pall Mall smoker keeps birds.
define C7 \$[yellow ~\$Cigarette Dunhill];
# The owner of the yellow house smokes Dunhills.
define C8 [House^2 ~\$Drink milk ~\$Drink House^2];
# The man in the center house drinks milk.
define C9 [? Norwegian ?*];
# The Norwegian lives in the first house.
define C10 \$[Blend ? ~\$Pet cats | cats ~\$Cigarette Blend];
# The Blend smoker has a neighbor who keeps cats.
define C11 \$[horses ~\$Cigarette Dunhill | Dunhill ? ~\$Pet horses];
# The man who keeps horses lives next to the Dunhill smoker.
define C12 \$[bier BlueMaster];
# The man who smokes Blue Masters drinks bier.
define C13 \$[German ~\$Cigarette Prince];
# The German smokes Prince.
define C14 \$[Norwegian ~\$Color blue | blue ? ~\$Nationality Norwegian];
# The Norwegian lives next to the blue house.
define C15 \$[Blend ~\$Drink water | water ? ~\$Cigarette Blend];
# The Blend smoker has a neighbor who drinks water.

All that we need to do to solve the problem is to impose the constraints on the row of five houses by intersection. The solution below is almost correct.

define Solution [House^5 & C1 & C2 & C3 &C4 & C5 &
C6 & C7 & C8 & C9 & C10 &
C11 & C12 & C13 & C14 & C15];

The result is a network with five paths. In four of the solutions nobody keeps fish and the German keeps the same kind of pet as someone else. We need one final constraint, presupposed by the question Who keeps fish?:

define C16 \$fish;
# There is someone who keeps fish.

With C16 added, only one solution remains. To make it easier to see, we compose the solution with the transducer that adds some prose around the pieces along the one remaining path:

We can now see the solution.

In the yellow house the Norwegian drinks water, smokes Dunhills,
and keeps cats.
In the blue house the Dane drinks tea, smokes Blends,
and keeps horses.
In the red house the Englishman drinks milk, smokes PallMalls,
and keeps birds.
In the green house the German drinks coffee, smokes Princes,
and keeps fish.
In the white house the Swede drinks bier, smokes BlueMasters,
and keeps dogs.

In short, it's the German who keeps fish.
Left by Terence on Apr 30, 2009 9:35 AM

# re: Einstein's Puzzle
All of you are so competitive about this relax.
For those who used a program I have to agree you did not solve this. But for those who either did it in their head, or wrote it on paper;then congrats! Just don't make a big deal over it. We are all smart. I completed this on paper in around 45 mins while talking to a friend on IM and listening to music.
Left by Stephen G on May 06, 2009 9:44 PM

# re: Einstein's Puzzle
the german owns the fish , about 15 minutes
Left by Shideh on Jul 22, 2009 9:54 AM

# re: Einstein's Puzzle
helllllloooooooooo!?? I'm sorry but this is not a very hard puzzle at all. In fact, it hardly stretches the mental capacity of the average 21st millenium homo Sapien. And quite frankly it bored me. I don't think Einstein was that smart, he was just a guy who hit upon a very interesting idea. I'm 12 and some people at cambridge, where I get tutored in the holidays, found it difficult. And that was supposed to be the equivalent of an ivy league or something. Oh, and by the way, England sucks!
Left by Paris on Aug 03, 2009 4:35 AM

# re: Einstein's Puzzle
Not to be a nob but I used pen and paper (barely, most was done in my head) and I got German in just less than six minutes. Wasn't difficult at all, just required you to jot down some notes.
Left by Greg on Aug 29, 2009 2:32 AM

# re: Einstein's Puzzle
hi,
your blog is really very informative and helpfull for people who are searching related information
Left by Cheap Textbook on Nov 25, 2010 10:49 PM

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