Einstein’s Challenge is something that I had heard sometime in my life, but never checked it out…until one of our developers emailed it to the development staff this week.  I was intrigued, since I love puzzles and deductive logic is my favorite brain exercise.

If you want the puzzle itself, do three things:

  • Be honest with yourself and don’t Google the answer ahead of time.  This was good advice from the developer who sent it, and I’m glad I followed it rather than looking for a quick way out.
  • Don’t worry about whether it’s from Einstein or not.  I’m sure someone slapped his name on the puzzle at some point to draw public interest.
  • Go to this page to read the puzzle, and don’t click the link to go to the solution (yet)…Einstein’s Challenge (GreyLabyrinth.com)

I solved it without any help, so I guess that puts me in the 2% category–whatever that means.  I have also had various IQ tests on cereal boxes rate me at 144 or above, but I guess the results of those tests are far more reliable if you take the test before you reach your 40’s.

I really liked this puzzle.  I was not only surprised at how much I learned about my own approach to solving the puzzle, I have also enjoyed watching other people try to solve it.  Not only are there different approaches taken by different people, but watching people’s body language when they are perplexed is really amusing.  If you put my wife’s scratch paper next to mine, you will see two entirely different sets of diagrams and notes.  I still don’t understand her line of thinking, but she did solve it.  I guess the result justified the means.

Read on only if you’ve tried the puzzle and solved it–or given up.  I’ll share with you how my mind approached the problem: I’ll leave the judgment of efficient or inefficient to you.

Reading and Absorbing

As I read through the description of the problem, the FACTS OF THE PUZZLE were describing five entities, with five unique items–one item from each of five groups.  That was easy.

And as I read the facts which had to be true, I began finding myself fighting prejudice and stereotypes in my thought.  This was somewhat expected, because I have an associative mind: part of that from training in Military Intelligence, most of it from watching Robin Williams too much.

The real trick to solving a problem is rational thinking, and a lot of questions instead of assumptions.  So I would read about the Swede and the Norwegian and think their houses must be log cabins with mud roofs, or that it was weird that the Dane drank the tea instead of the Britt.  So I had to quickly admit to myself that part of solving the puzzle was to avoid preconception as a means of self-deception.

Towards the end of the facts, I noticed a pattern of 5 in all the “who owns what” descriptions, except for pets which had only four.  So the question of “Who has the fish”(which sounds like something out of Monty Python–associative mind again) didn’t throw me off.  It was obvious that it would reveal itself by the process of elimination.

So I took what I grasped from the concept, and drew five boxes, left to right (I figured that was important since the Norwegian lived in the left house–not the top house).  In each of the houses, I drew five lines to represent the properties of the house.  Line 1 for Nationality, line 2 for house color, line 3 for liquid, line 4 for pet/livestock, and line 5 for tobacco product.

BTW: I consider a horse livestock, not a pet.  A pet can stay in the house with you, and if you have a horse that really is your pet, I won’t be visiting you anytime soon.

The Solving Process

I found it quite easy to determine the color of the houses from facts 9, 15, 4, 5 and 7 (the latter mentions the fifth color of Yellow).  After I had done this, I didn’t like the jumping around I was doing in the list of facts, and I found myself wanting to reorder/regroup the facts, thinking that might keep the solution more logical.  But I realized there was really nothing to gain by that, so I just took a pen and crossed off those I was sure was right and kept the order as it appeared.  I remembered an old adage at this point: focus on the accomplishment, not the activity.

After establishing which house was which color, the Yellow house (7) led to Dunhills (7), which led to horses  (11).  No problem there.  At this point, the obviously easy fits come to an end.  Looking at the other facts, it’s clear there are multiple fits that are possible in all cases.  This is probably the point in the exercise where it becomes difficult for the 98% who don’t solve it.

And I notice a peculiar thing: two of the clues show an association to a common item: Blend and Water are in neighboring houses, and Blend and Cats are also in neighboring houses.  But I also smell something fishy, which could be a good thing: maybe it helps to find the house with the fish.

As I visualize the description in my head and draw out the relations as circles with connecting lines, I see two possibilities: either Blend has water on one side and cats on the other side, or both water and cats are actually in the same house.  So my first reaction is to read the text again:  does it exclude the possibility that the two (water and birds) belong in the same house.  No, the text does not exclude it.

I see the potential for being caught in a maze because of an ambiguity here.  In a maze, you have three pieces of information: there is an entrance, there is an exit, and there is a unobstructed path between the two.  But there are, of course, a number of obstructed paths that you can take which are are wrong.  A maze has to be solved by trial and error: a wrong turn in the maze leads to a dead end, and requires a certain amount of backtracking before trying another route.  The way to make this easier is to mark the trails you have tried, so there is some history of past failures to refer to when deciding on another path to try.

I realize that some trial and error will now come into play at this step, so I copy what I have (i.e. what I am sure of) to a separate paper, and treat it as my test area.  I also now use a pencil.  These are my breadcrumbs.

I decide to go with a hunch that cats and water are in the same house is probably right, since it is not obvious. That’s just from experience with past logic problems: they try to trick you like that.  Now my important decision: do I test for the negative (separate houses which I think is wrong), or the positive (same house which I think is right).

I decide to test for the negative: I assume different houses, and check a few possible combinations of tobacco, drinks, people, etc, in the leftover spots to verify that I get consistent dead ends every time.  Each time I did this (luckily it was only twice), that was what happened.

So I go back to the combination I think is right: that water and cats belong in the same house.  I initially put them in house 5, and that hits a dead end.  The only other place they logically can go is in house 1, and then all of the other clues just fall into place–at least for me.


I’m not sure the step of checking for the negative was the best choice, but it didn’t matter with the pencil: I was quickly correcting errors, and the “what if” approach also helped me to see patterns and pairings in the remaining clues.  So I felt it was worth the extra time.

The real challenge I had in solving this puzzle was putting a stop to the creative thinking, and just use objective thinking. and pure deductive logic: i.e. stick to the facts.  Drawing things out on paper was the best way to enforce that discipline.


Later on my wife showed the puzzle to my sons. My 18 year old solved it this evening in 20 minutes.  It is now late in the evening and my 15 year old son, after 30 minutes on the problem, has just blurted out that he is convinced the Norwegian lives in either a yellow or a white house.   I may have to impose a cut-off time tonight, but I admire his tenacity.