Einstein's Riddle (A Challenging Logic Puzzle)
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I solved it around a year ago within an hour using Excel as well. This is difficult but not impossible and you are right, I believe that a much bigger percentage of people can solve this. But I doubt that the percentage of successful people will go over 15%. However, in this forum a lot of us will solve it simply because well, we are programmers :-\ . On a serious note, we tend to think a lot more logically than others.
Nice. I just posted this as a challenge on Facebook and one of my friends apparently solved it in 40 minutes. I like to think that's because he didn't have to deal with his cat distracting him (it was distracting me instead!). :rolleyes:
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
My favourite solution is SQL based: http://www.sqlteam.com/article/another-german-yak-with-a-suprise-rc-3[^]
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
It helps if you do Sudoku regularly. Less than 30 mins on paper!
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It helps if you do Sudoku regularly. Less than 30 mins on paper!
Our boss gave it to us last year, I did it in around half an hour using pen and paper. Apparently he was thinking of giving it to interviewees as part of some logic tests they are asking them to do now.
Every man can tell how many goats or sheep he possesses, but not how many friends.
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
It took me 35 minutes. Good puzzle...
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
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It helps if you do Sudoku regularly. Less than 30 mins on paper!
It took me about the same, including preparation time, using sticky notes on a 5 x 6 grid on my white board. I reckon this is the easiest way to do it, as you can stick the notes together corresponding to each clue. Drawback? I now need to buy another pad of stickies. :-\
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
45 min on paper. Probably would have been faster if my manager hadn’t interrupted me wondering what I was doing. And going by the sound coming from his office right now, he is attempting it himself.
saru mo ki kara ochiru (even monkeys fall from trees) Usualy i'm that monkey. If you want an intelligent answer, Don't ask me. To understand Recursion, you must first understand Recursion.
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
Took about 5 minutes with pen and paper. In fairness, I've solved this one about 20 years ago on napkins in the lunch room at school. Another fun "riddle" I remember from back then - albeit a much simpler one - is this one: A mathematics student in financial trouble sent a telegram to his (wealthy) father asking for money. Not having enough cash to send a long telegram, and knowing his father would appreciate a mathematical riddle, he sent the following: Dad, SEND + MORE =MONEY Thanks! How much did he need? To my knowledge there is only one logically sound solution to this. After solving it I made a pascal routine to solve it, and came up with a number (I seem to remember 24) of alternative solutions. Common to all of them was that they were somewhat logically flawed, although mathematically correct. //L
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
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It helps if you do Sudoku regularly. Less than 30 mins on paper!
Yup. Doing that sort of problem with Matrices is much easier than trying to match up the clues to solve one item at a time; but I've never seen any examples of how to do it that way in books or online. (I learned the approach from my gifted teacher in school.)
3x12=36 2x12=24 1x12=12 0x12=18
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It helps if you do Sudoku regularly. Less than 30 mins on paper!
Tom Lawton wrote:
It helps if you do Sudoku regularly
Haha, that's what my friend said.
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:cool: ~20 mins for me... used Excel but not for anything I couldn't have done by drawing out some columns on a piece of paper (albeit slower - no copy n paste). Thanks for posting :-)
Not bad, not bad at all!
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aspdotnetdev wrote:
Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists?
Or that only 2% of the population could do it entirely in their head? :)
Doing it entirely in my head would probably take a good long while.
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It helps if you do Sudoku regularly. Less than 30 mins on paper!
I agree with you. Train your logic and it will be an easy riddle for you! By the way, Sudoku is a part of Japanese school program, as far as I remember.
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
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One of the emails CP sends out linked to this (don't scroll too far down or you'll see the answer). Usually, I would be most interested in the programming portion, but for this particular puzzle I found the logic to be the most interesting part, so I decided to solve it myself. I solved it in 1 to 2 hours, but I'm not entirely sure if I cheated or not. Basically, I solved as much of it as I could using logic, then I tried a few possible combinations until I got a result that satisfied all the criteria (I assumed there was only 1 solution). Since I did it by hand (well, using Excel to quickly copy/paste), I'm thinking it wouldn't be considered cheating. In any event, it's a fun puzzle and I encourage you all to attempt it when you have a bit of time to focus (and report the results back here!). Also, that 98% of people would not be able to solve this seems silly. Do you think he meant 98% of people would not be able to solve this within a certain timeframe? Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists? If you want to see a solution fully explained, see here. Also, Wikipedia explains the solution to a variant of the puzzle. I have not read either, but thought I'd include those links for you more, erm, productive individuals. ;)
Took me a pencil, about half a page of hand-scribbled notes, and roughly 15 minutes to solve. My method involved figuring out a method to encode the statements into a Sudoko-like scheme (i. e. for every attribute I wrote down the list of house numbers they might be associated to) and then using the basic mechanics of exclusion to strike off every option that couldn't work until I ended up with an attribute that had only one option left. I created a table for the houses and attributes I already found out for each of them as an easy way to look up which of the attributes I already know of a house would conflict with a given statement. That is also how I would have solved it using Prolog. Not sure what the language was the author used, but the program looked awfully long and unneccessarily complicated. Would have been a lot shorter in Prolog! (although the neighbourhood relations might have been difficult to encode in Prolog as well) Regarding the 98% statement - I can easily believe that 90% of all people wouldn't know where to even start, as their skills to analyze a problem or logically reason is way below that of someone who came into contact with that kind of stuff beyond school. Any computer scientist, mathematician, and even most programmers without an academic degree know the basic tools required to solve this kind of problem, but very few other people have. The remaining 10% I would expect to be theoretically able to solve the problem, given enough time, but many might give up because they didn't come up with a suitable way to encode the problem, or kept on trying to solve it using direct implications, instead of looking at exclusion mechanisms. I'd still expect most of these people *could* solve it if their live depended upon it, and maybe after a good night's sleep ;)
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aspdotnetdev wrote:
Or maybe that only 2% of people could prove their solution without making the simplifying assumption that only one solution exists?
Or that only 2% of the population could do it entirely in their head? :)
lol, I'm pretty good at doing stuff in my head (even played chess 'blindly' a few times when I was younger), but that would indeed have taken me quite some time :laugh: I like writing down things when I'm thinking, I found it helps getting a clearer picture of a problem when I try to formulate it, even if it's only on paper.
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lol, I'm pretty good at doing stuff in my head (even played chess 'blindly' a few times when I was younger), but that would indeed have taken me quite some time :laugh: I like writing down things when I'm thinking, I found it helps getting a clearer picture of a problem when I try to formulate it, even if it's only on paper.
There is no way I could do this in my head, but I did solve it with pencil and paper in under an hour. I didn't time it exactly.