# Comment On More Limitin', Wrong Major, and Parallel Universe Replacement

More Limitin' (from Andrew Warren-Love) Even though his resume wasn't beaming as much as some of the others we received, we invited a man down to interview for either of two positions. One in the IT Department and one in the Software Group of the Engineering Department. Once he arrived, he was given a tour of the important parts of the company to encourage interest related to our company or our products just like everyone else we interview. By this point, 90% of candidates will ask questions on their own, and the rest will ask questions when prompted. [expand full text]
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### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 07:17 • by Paddy Ryan (unregistered)
 The real tricky one is 12 in 3 balances (all outcomes covered)

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 07:51 • by Richard (unregistered)
 Mathlete :This is just plain wrong. Yes, I'm a feckin' eejit. I meant to write CEIL(Log(N)/Log(3)) - aka CEIL(Log3(N)) - which is correct when you *do* know whether the fake coin is heavier or lighter.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 07:55 • by QJo
 Anchors aweigh:The question usually assumes a balance scale (at least for the 8 weight issue). For that: 1) Weigh A+B+C vs D+E+F. If they are equal then G or H are heavier. 2) If G or H are heavier, then obviously weigh them against each other. 3) If G and H are the same, then repeat the step one with the heavier triad, but leaving one out. So 2 weighings for 8 on a balance scale. Step 2 is flawed. G and H are obviously going to weigh differently. Which is which? You don't know. What you can do is weigh A against G, and if G is lighter/heavier then G's the odd one, if not then H is - but you can't know whether H is heavier or lighter.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 07:58 • by Tarl (unregistered)
 Paddy Ryan:The real tricky one is 12 in 3 balances (all outcomes covered)I assume this is an important problem because you are selling live chickens from your farm in Ye Olde Common Marketplace for 12 Copper Tarsks each, and you suspect the Warrior in front of you (smartly equipped with red tunic and steel sword) is attempting to defraud you by sneaking in one Copper Tarsk that has been slightly shaved around the edges. 1. How do you know he didn't offer you two shaved coins? 2. You brought your scales, but forgot to bring a Reference Tarsk? 3. Since your prices aren't posted, tell everyone else the price is 12 C.T. but tell the Warrior 13. Then it doesn't matter if one of them is bad. 3A. If, in talking to others at the Marketplace, the Warrior learns you are selling chickens for 12 CT to everyone but him, offer him a 1 CT refund. Now he has to sweat that you might give him the false CT! 4. He's a Warrior goddammit! When you get out the balance and start playing tiddly winks, he will know you are essentially accusing him of fraud. He's standing and you are seated behind your counter. Just give him the chicken already and rejoice that he allows you to keep your head!

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 08:29 • by Cishuman (unregistered)
 The first one is just wrong. After all, HTML + CSS is Turing Complete, and therefore it is in principle possible to write a Java interpreter in it...

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 08:46 • by Larry (unregistered)
 Cishuman:The first one is just wrong. After all, HTML + CSS is Turing Complete, and therefore it is in principle possible to write a Java interpreter in it...So is HTML + JavaScript; but he didn't say "HTML plus some language is limitin" he said "HTML is limitin".

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 08:57 • by this socks (unregistered)
 dkf:It goes something like this: You've got a box with a bunch of lights in it, one of which is broken. The box is opaque and openable; a switch in the hinge mechanism ensures that no electricity is flowing through the circuit when the lid is open. How do you work out which light is broken so you can fit the replacement? The answer's obvious and trivial to remember once you know it; it's a stupid “A-ha!” question that reveals that the interviewer isn't very good at it. A good interview question should be either genuinely tricky or thoroughly open-ended; in the former case, you're testing whether they actually know what they claim, and in the latter case you'd be looking for whether the interviewee identifies the major strategies for tackling the problem. The only correct answer is: "Don't replace the lightbulb, it's inside a box and completly useless. Why change it?" Think outside the box.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:07 • by The poop of DOOM
 this socks: dkf:It goes something like this: You've got a box with a bunch of lights in it, one of which is broken. The box is opaque and openable; a switch in the hinge mechanism ensures that no electricity is flowing through the circuit when the lid is open. How do you work out which light is broken so you can fit the replacement? The answer's obvious and trivial to remember once you know it; it's a stupid “A-ha!” question that reveals that the interviewer isn't very good at it. A good interview question should be either genuinely tricky or thoroughly open-ended; in the former case, you're testing whether they actually know what they claim, and in the latter case you'd be looking for whether the interviewee identifies the major strategies for tackling the problem. The only correct answer is: "Don't replace the lightbulb, it's inside a box and completly useless. Why change it?" Think outside the box. Maybe it's a simulation to find the answer to the question if the light in the fridge goes out when you close the door. Then you should fix it to make sure your tests are valid.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:09 • by pjt33
 dkf: The poop of DOOM:I never actually heard the lightbulbs thing. How does that one go?It goes something like this: You've got a box with a bunch of lights in it, one of which is broken. The box is opaque and openable; a switch in the hinge mechanism ensures that no electricity is flowing through the circuit when the lid is open. How do you work out which light is broken so you can fit the replacement? Most people seem to be answering a different lightbulb question. You have three switches, and three lightbulbs in a box. Each switch controls one lightbulb. You are allowed to look in the box precisely once. How can you work out which switch controls which lightbulb?

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:11 • by Peter (unregistered)
 Tarl:I assume this is an important problem because you are selling live chickens from your farm in Ye Olde Common Marketplace for 12 Copper Tarsks each, and you suspect the Warrior in front of you (smartly equipped with red tunic and steel sword) is attempting to defraud you by sneaking in one Copper Tarsk that has been slightly shaved around the edges.Tarl? Would that be Tarl Cabot, Tarnsman of Gor? Oh God, I'm so embarrassed that I caught the reference...

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:16 • by QJo
 Peter: Tarl:I assume this is an important problem because you are selling live chickens from your farm in Ye Olde Common Marketplace for 12 Copper Tarsks each, and you suspect the Warrior in front of you (smartly equipped with red tunic and steel sword) is attempting to defraud you by sneaking in one Copper Tarsk that has been slightly shaved around the edges.Tarl? Would that be Tarl Cabot, Tarnsman of Gor? Oh God, I'm so embarrassed that I caught the reference... I believe he may be travelling incognito under the alias Bosk ... You will find him by the trail of meek, submissive, exquisitely-ringed and -silked slave girls he leaves in his wake.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:24 • by MrBester (unregistered)
 You get someone else to look in the box each time a switch is turned "on" (this assumes that the lights are off to begin with). This only needs to happen twice. Then you get to look in the box and marvel at the stupidity ad pointlessness of making an opaque box containing light bulbs that can be switched on when the box is closed.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:31 • by CrisW
 Puzzles:Whenever I see someone bring up that lightbulb puzzle, I feel compelled to point out that the puzzle itself is fundamentally broken. The normal assumption in a puzzle is that all the components are ideal, because the story is really just window-dressing on an ABSTRACT puzzle. If something is in an opaque box, you can't peek through a crack. If something has an on/off switch, you can't hold it in some middle position that makes intermittent contact. If you don't make those kinds of assumptions, these puzzles generally have a huge number of possible solutions, most of which are uninteresting and rely on circumstances not specified in the problem statement. The accepted solution of the lightbulb puzzle is to check the temperature of the bulbs. But that relies on an arbitrary non-ideal assumption (non-negligible waste heat) that isn't stated in the problem, so that's no more legitimate an answer than "I peek through a crack in the box" or "I trace the wires to see what's connected to what". It's arguably not even a REASONABLE assumption these days--what if the lights are LEDs? Lateral thinking puzzles don't generally belong in interviews, but that particular puzzle doesn't even belong in a game of puzzles. If you got the "correct" answer without being told, that actually means you're WORSE at these puzzles than many of the people who didn't get it, because under the normal implicit rules, it doesn't have a solution. clcto:5 weights in 3 weighings? That doesn't require any level of brain power. Isn't the question 8 in 2 weighings? I imagine that puzzle has many permutations depending on the exact nature of the measurement tool you use and whether you are told in advance that the different weight is lighter or heavier or only that it is "different". 8 is likely a popular number because it is a power of 2, and therefore adds an extra red herring to the puzzle. Light bulbs don't give out any detectable heat any more. (well, not so that you could detect it by touch anyway.)

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:32 • by Bulby McBulb (unregistered)
 MrBester:Then you get to look in the box and marvel at the stupidity ad pointlessness of making an opaque box containing light bulbs that can be switched on when the box is closed. Probably that same idiot who wired up the bulb in the sock drawer puzzle

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 09:40 • by Mastur Plan Software (unregistered)
 I would grab as many socks as possible. Also, I may be suffering from "puppeteer's bias".

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:00 • by geoffrey (unregistered)
 this socks: dkf:It goes something like this: You've got a box with a bunch of lights in it, one of which is broken. The box is opaque and openable; a switch in the hinge mechanism ensures that no electricity is flowing through the circuit when the lid is open. How do you work out which light is broken so you can fit the replacement? The answer's obvious and trivial to remember once you know it; it's a stupid “A-ha!” question that reveals that the interviewer isn't very good at it. A good interview question should be either genuinely tricky or thoroughly open-ended; in the former case, you're testing whether they actually know what they claim, and in the latter case you'd be looking for whether the interviewee identifies the major strategies for tackling the problem. The only correct answer is: "Don't replace the lightbulb, it's inside a box and completly useless. Why change it?" Think outside the box. That's not thinking outside the box. It's thinking pragmatically. I would give you points for your ability to triage a situation. Not all defects need to be fixed.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:01 • by Quant Ummm (unregistered)
 Look, as long as the box is closed, you can't observe the light bulbs so there is a 50% chance that each one is on or off. More precisely, each one is 50% on and 50% off until you open the lid, at which point the universe tosses a coin (of full standard weight) and the wavefunction resolves. Just make sure someone is watching you open the lid, so your wavefunction resolves to ensure your own existence. That's why I always have someone watch me while I watch porn.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:05 • by golddog
 When I took the socks out of the laundry, I would bundle them into matching pairs before putting them in the drawer. 100% that I'll get a matched pair.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:09 • by QJo
 airdrik: geoffrey: Puzzles:Whenever I see someone bring up that lightbulb puzzle, I feel compelled to point out that the puzzle itself is fundamentally broken. ... The point of the light bulb puzzle is that it is best to go down the path of least resistance first. Maybe the bulbs do not put out heat, but given that most do, it is an option with a high probability of success. I'm more interested in someone who will troubleshoot through experimentation and observation, and who will not be more interested in the elegance or cleverness of the solution than in solving the problem at hand. It is still a fundamentally broken puzzle - it relies on assumptions about particular light bulbs (yes the most common type, but alternatives are readily available and that common type is approaching a rapid decline). While most candidates will have had some experience with a heated bulb (who hasn't changed a light bulb just after turning it off, or tried while it was still on), slim few are going to make the required leap to the assumption made by the puzzle to make it solvable. There are plenty of other puzzles which don't have some catch to them from which the puzzle draws assumptions and requires familiarity with the catch to solve. One is almost tempted to say to the interviewer: "In such a set of circumstances, I would ask myself: What would Jesus do?"

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:13 • by Cishuman (unregistered)
 Eh, just change all light bulbs. The beancounters will complain about the cost, but who cares about that, amiright?

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:19 • by Pommes-Frites Avec (unregistered)
 I would use a tricorder to determine the odd weight out and which lightbulb in the box is broken. I don't think they work on socks but since their display gives off light I can use that to get a matching pair with only two socks, a 50% improvement over the stated goal! My solutions not only show my out-of-the-box thinking and imagination, but also my wittiness because I said "out-of-the-box" while dealing with lightbulbs that are in a box.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:29 • by A Gould (unregistered)
 geoffrey: The point of the light bulb puzzle is that it is best to go down the path of least resistance first. Maybe the bulbs do not put out heat, but given that most do, it is an option with a high probability of success. That's an assumption that is only going to get worse, and it begs the question - if you're giving me physical access to the bulbs and the switches, why don't I have access to the wiring? It's also a question that assumes that you're willing to play with electricity with no gear. Always wondered why this would be considered a desirable trait, considering how high Worker's Comp premiums can go...

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:29 • by boog
 QJo:One is almost tempted to say to the interviewer: "In such a set of circumstances, I would ask myself: What would Jesus do?"That ought to change the subject! On that note: Q: Why are manhole covers round? A: Because God made them that way.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:32 • by Mastur Plan Software (unregistered)
 boog: Q: Why are manhole covers round? I prefer my manholes uncovered.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:33 • by trtrwtf
 Cishuman:Eh, just change all light bulbs. The beancounters will complain about the cost, but who cares about that, amiright? They won't complain when you compare the cost of developer time to the cost of light bulbs, and when you point out that you can donate the old bulbs to some poor but noble charitable organization and get a tax advantage plus good fodder for the goodwill advertising. Picture it! The dark screen, suddenly illuminated, and we see a hand pulling away from a light bulb. Scenes of people doing Important Work, all of them illuminated by light bulbs in subtly prominent positions in shot. Moves into a montage of young and ethnically-diverse staff people helping younger and slightly less ethnically-diverse blind indigent tap dancers to perfect their steps in a brightly-lit dance studio, as the voiceover comes in: "SymBoolean is proud to support the efforts of the home for blind indigent tap dancers. SymBoolean... helping everyone to look on the bright side of life!" Followed of course by the fast disclaimer mumble: "...except when there isn't a bright side because the light bulb doesn't work, but hell, they're blind, what do they need light bulbs for? whaddaya want from us, blood?" At least, that's what I'm spending my morning on, 'cause nothing much is going on the day before the holiday weekend.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:36 • by Rootbeer
 First, challenge the interviewer to justify the purpose of the box with light bulbs inside it. If it doesn't serve a legitimate business function, then performing any maintenance on it whatsoever is a waste of company time and it should be decommissioned. But let's say for argument's sake that it's part of an industrial cookie-making machine. The uncooked rounds of dough travel along a conveyor belt, where they are cooked to a perfect golden brown by a gauntlet of infrared lamps; if one of the lamps has stopped working, then cookies are ruined and the company loses money. This scenario also validates the assumption that these lamps give off a discernible amount of heat. Opening the box to determine which lamp has malfunctioned requires the entire line to be shut down, which also costs the company money, explaining the restriction that the box can only be opened and observed once. The solution as typically given is only part of the full solution. After the errant bulb has been replaced, the next step is to check the maintenance logs and see who is responsible for the switches being installed improperly; each should be labeled, and each should have the same orientation. Find that person and fire them. If insufficient logs exist, find the person responsible for the maintenance logs and fire them. Finally, fix the actual problems. Re-install the switches correctly, label each one, and wire up an external indicator lamp in series with each infrared lamp, so that in the future when a lamp dies, it will be immediately obvious which one. Now you have more time to work on optimizing the machine that figures out which of the 6 million cookies manufactured today is outside of the acceptable weight range.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:41 • by Jeff (unregistered)
 Rootbeer:if one of the lamps has stopped working, then cookies are ruined and the company loses money.An elegant scenario, but FFS if the company depends on the bloody light bulbs, have some redundancy! You ought to be able to hot-swap up to N/2-1 bulbs without shutting down the line!

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:42 • by Mr Zip (unregistered)
 Herby:Puzzles... One time when I was in an airport lounge, I noticed a math teacher giving quizzes to his group of students. Being the helpful type, I answered them before he could get the whole puzzle out. It felt real good for me (a bystander) and you could see the math teacher fuming that I knew the answers. The two puzzles were: You have a bunch of socks in a drawer, (usually 10 black, and 10 brown), how many socks does it take to get a proper pair to wear. Answer: 3. A tree is dropping leaves as the season progresses. Each day it drops twice as many as the day before. Assuming that it always drops the maximum numbe, on which day do most of the leaves drop. Answer: last day. I was smiling as I went to the plane. What if my tree has 1025 leaves? You need to give me a probability distribution of leaf counts in the population of trees to be able to assess whether the most leaves drop on the last day or second to last day.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 10:54 • by trtrwtf
 Rootbeer: But let's say for argument's sake that it's part of an industrial cookie-making machine. The uncooked rounds of dough travel along a conveyor belt, where they are cooked to a perfect golden brown by a gauntlet of infrared lamps; if one of the lamps has stopped working, then cookies are ruined and the company loses money. ... Opening the box to determine which lamp has malfunctioned requires the entire line to be shut down, which also costs the company money, explaining the restriction that the box can only be opened and observed once. If one of the bulbs has gone on strike, then fire any idiot who's running the machine and wasting cookie dough while the machine is not working. Then fire the maintenance guy who's apparently sitting on his thumbs instead of fixing the damned busted bulb by opening the box and turning on the switches until he finds the busted one. And then re-hire him and fire him again for not having an effective schedule for bulb replacement. These bulbs should be replaced before they hit expected end-of-life, not after they fail. Then fire everyone in the place and outsource the thing to Hyderabad and ship the cookies back to the states. Nagesh, we have work for you!

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:02 • by Nagesh
 trtrwtf: Rootbeer: But let's say for argument's sake that it's part of an industrial cookie-making machine. The uncooked rounds of dough travel along a conveyor belt, where they are cooked to a perfect golden brown by a gauntlet of infrared lamps; if one of the lamps has stopped working, then cookies are ruined and the company loses money. ... Opening the box to determine which lamp has malfunctioned requires the entire line to be shut down, which also costs the company money, explaining the restriction that the box can only be opened and observed once. If one of the bulbs has gone on strike, then fire any idiot who's running the machine and wasting cookie dough while the machine is not working. Then fire the maintenance guy who's apparently sitting on his thumbs instead of fixing the damned busted bulb by opening the box and turning on the switches until he finds the busted one. And then re-hire him and fire him again for not having an effective schedule for bulb replacement. These bulbs should be replaced before they hit expected end-of-life, not after they fail. Then fire everyone in the place and outsource the thing to Hyderabad and ship the cookies back to the states. Nagesh, we have work for you! Your atitude is very demeening. Sorry!

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:09 • by trtrwtf
 Nagesh: trtrwtf: Rootbeer: But let's say for argument's sake that it's part of an industrial cookie-making machine. The uncooked rounds of dough travel along a conveyor belt, where they are cooked to a perfect golden brown by a gauntlet of infrared lamps; if one of the lamps has stopped working, then cookies are ruined and the company loses money. ... Opening the box to determine which lamp has malfunctioned requires the entire line to be shut down, which also costs the company money, explaining the restriction that the box can only be opened and observed once. If one of the bulbs has gone on strike, then fire any idiot who's running the machine and wasting cookie dough while the machine is not working. Then fire the maintenance guy who's apparently sitting on his thumbs instead of fixing the damned busted bulb by opening the box and turning on the switches until he finds the busted one. And then re-hire him and fire him again for not having an effective schedule for bulb replacement. These bulbs should be replaced before they hit expected end-of-life, not after they fail. Then fire everyone in the place and outsource the thing to Hyderabad and ship the cookies back to the states. Nagesh, we have work for you! Your atitude is very demeening. Sorry! Okay, you're fired. Shiva, we have work for you!

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:11 • by boog
 Mastur Plan Software: boog: Q: Why are manhole covers round? I prefer my manholes uncovered.Another discomforting answer - just be sure to wink at the interviewer, for added hilarity.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:12 • by not frits at all (unregistered)
 What was his favorite project to work on? "Uhh, they're'll'bout the same." Well, I had a "friend" who was afflicted with advanced indecision disorder, and let me assure you that either: a) It is no laughing matter b) It is funny as hell c) I don't remember Decide for yourself.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:21 • by Nagesh
 boog: Mastur Plan Software: boog: Q: Why are manhole covers round? I prefer my manholes uncovered.Another discomforting answer - just be sure to wink at the interviewer, for added hilarity. Manhole cover is round because the mold to make them is round. If mold to meke them is square, then you can have square or rectangle or any shape you like.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:25 • by geoffrey (unregistered)
 A Gould: geoffrey: The point of the light bulb puzzle is that it is best to go down the path of least resistance first. Maybe the bulbs do not put out heat, but given that most do, it is an option with a high probability of success. That's an assumption that is only going to get worse, and it begs the question - if you're giving me physical access to the bulbs and the switches, why don't I have access to the wiring? It's also a question that assumes that you're willing to play with electricity with no gear. Always wondered why this would be considered a desirable trait, considering how high Worker's Comp premiums can go... Why you don't have access to the wiring is irrelevant. You do not get to dictate the conditions under which you can solve a problem. This quiz weeds out the bystanders from the go-getters. Case in point.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:27 • by QJo
 geoffrey: A Gould: geoffrey: The point of the light bulb puzzle is that it is best to go down the path of least resistance first. Maybe the bulbs do not put out heat, but given that most do, it is an option with a high probability of success. That's an assumption that is only going to get worse, and it begs the question - if you're giving me physical access to the bulbs and the switches, why don't I have access to the wiring? It's also a question that assumes that you're willing to play with electricity with no gear. Always wondered why this would be considered a desirable trait, considering how high Worker's Comp premiums can go... Why you don't have access to the wiring is irrelevant. You do not get to dictate the conditions under which you can solve a problem. This quiz weeds out the bystanders from the go-getters. Case in point. "Do you want me to fix the stupid light-bulb? Then get out of my way and let me get on with the damn job!"

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:30 • by Behold My Final Form! Zunesis! (unregistered)
 Mastur Plan Software:I would grab as many socks as possible. Also, I may be suffering from "puppeteer's bias".I like tube socks, too, but it has nothing to do with puppets. I also enjoy putting them back in someone's drawer when I'm done - you know, icing on the cake.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:40 • by CodeRage
 Actually, the hardest problem is 12 weights, 3 weighings, and you do not know if the odd one is heavier or lighter. I don't know how that fits into the general solution, but there is a solution for this.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:45 • by no laughing matter
 not frits at all:What was his favorite project to work on? "Uhh, they're'll'bout the same." Well, I had a "friend" who was afflicted with advanced indecision disorder, and let me assure you that either: a) It is no laughing matter b) It is funny as hell c) I don't remember Decide for yourself. Well for sure i know a) falls out of the scope, but i cannot really decide between b) and c) because: a) i cannot remember if i have already decided b) would be funny, but i am no laughing matter, so this would be a contradiction.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:49 • by Cantabrigian
 Mr Zip: Herby:Puzzles... One time when I was in an airport lounge, I noticed a math teacher giving quizzes to his group of students. Being the helpful type, I answered them before he could get the whole puzzle out. It felt real good for me (a bystander) and you could see the math teacher fuming that I knew the answers. The two puzzles were: You have a bunch of socks in a drawer, (usually 10 black, and 10 brown), how many socks does it take to get a proper pair to wear. Answer: 3. A tree is dropping leaves as the season progresses. Each day it drops twice as many as the day before. Assuming that it always drops the maximum numbe, on which day do most of the leaves drop. Answer: last day. I was smiling as I went to the plane. What if my tree has 1025 leaves? You need to give me a probability distribution of leaf counts in the population of trees to be able to assess whether the most leaves drop on the last day or second to last day. The puzzle says "Each day it drops twice as many as the day before", so the number of leaves on the tree must be of the form k(2^n - 1). (Strictly speaking there is no solution: the first day that any leaves fall fails to satisfy the condition.)

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 11:50 • by CodeRage
 Puzzles:Whenever I see someone bring up that lightbulb puzzle, I feel compelled to point out that the puzzle itself is fundamentally broken. The normal assumption in a puzzle is that all the components are ideal, because the story is really just window-dressing on an ABSTRACT puzzle. If something is in an opaque box, you can't peek through a crack. If something has an on/off switch, you can't hold it in some middle position that makes intermittent contact. If you don't make those kinds of assumptions, these puzzles generally have a huge number of possible solutions, most of which are uninteresting and rely on circumstances not specified in the problem statement. The accepted solution of the lightbulb puzzle is to check the temperature of the bulbs. But that relies on an arbitrary non-ideal assumption (non-negligible waste heat) that isn't stated in the problem, so that's no more legitimate an answer than "I peek through a crack in the box" or "I trace the wires to see what's connected to what". It's arguably not even a REASONABLE assumption these days--what if the lights are LEDs? Lateral thinking puzzles don't generally belong in interviews, but that particular puzzle doesn't even belong in a game of puzzles. If you got the "correct" answer without being told, that actually means you're WORSE at these puzzles than many of the people who didn't get it, because under the normal implicit rules, it doesn't have a solution. clcto:5 weights in 3 weighings? That doesn't require any level of brain power. Isn't the question 8 in 2 weighings? I imagine that puzzle has many permutations depending on the exact nature of the measurement tool you use and whether you are told in advance that the different weight is lighter or heavier or only that it is "different". 8 is likely a popular number because it is a power of 2, and therefore adds an extra red herring to the puzzle. The puzzle is not broken. The idea is to solve the problem without adding additional elements. From your examples, "I peek through a crack in the box" adds an element, a crack in the box. "I trace the wires" adds an element, some object that lets you trace the wires. The puzzle (this particular version) has these elements: you, a box, a switch, light bulbs Using only those elements, find the solution. Of course you have to make some RIDICULOUS assumptions, such as that you, a human, can detect heat. Or, that a light bulb holds its heat, and dissipates its heat in a reasonable amount of time. You know, like almost every light bulb ever made! But even with these RIDICULOUS assumptions, the correct solution is the most elegant, creative, and requires no additional elements added to the puzzle. Second, it's not just the solution that matters, but the process you go through to rule out those "extra elements", and to discover those "reasonable assumptions", that really leads to the "correct" solution. That is what the puzzle is about. Sorry you don't like the puzzle.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:02 • by pjt33
 trtrwtf:And then re-hire him and fire him again for not having an effective schedule for bulb replacement. These bulbs should be replaced before they hit expected end-of-life, not after they fail. You missed the step where you verify that the bulbs didn't fail before the expected end-of-life.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:07 • by no laughing matter
 Cantabrigian: The puzzle says "Each day it drops twice as many as the day before", so the number of leaves on the tree must be of the form k(2^n - 1). (Strictly speaking there is no solution: the first day that any leaves fall fails to satisfy the condition.) Strictly speaking there is a solution: ```2*0 = 0 ``` so we are talking about a conifer here!

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:10 • by trtrwtf
 pjt33: trtrwtf:And then re-hire him and fire him again for not having an effective schedule for bulb replacement. These bulbs should be replaced before they hit expected end-of-life, not after they fail. You missed the step where you verify that the bulbs didn't fail before the expected end-of-life. I don't care about that. I'm not firing him for bulbs failing, I'm firing him for not having a bulb replacement schedule. If he had a bulb replacement schedule, I'll fire him for something else. I don't like that guy. I don't like the cut of his jib, if you know what I mean.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:21 • by Behold My Final Form! Zunesis! (unregistered)
 trtrwtf:I don't care about that. I'm not firing him for bulbs failing, I'm firing him for not having a bulb replacement schedule. If he had a bulb replacement schedule, I'll fire him for something else. I don't like that guy. I don't like the cut of his jib, if you know what I mean. He's a flaming queer? This that what you mean? Or are you queer and would have preferred him un-cut? Now we see the true purpose of "rules": a means of establishing arbitrary authority to get rid of people you don't like.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:24 • by trtrwtf
 Behold My Final Form! Zunesis!: Now we see the true purpose of "rules": a means of establishing arbitrary authority to get rid of people you don't like. Yep. That's what we need around here - we need some rules.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:25 • by The Bytemaster
 Jellineck: Lucent: VeryBestDeveloperNumber1: Mmm, racism:LOL, it's funny because he has an accent!Racism, huh? I don't think I saw any mention of the interviewee's race. But yes, it's funny because he has an accent.No it's definitely racist because that's the way black people talk! I'm not sure he is black. He said "jarva", not purkles. I find the racisim comments funny. I was picturing a white guy in more of a cowboy hat... almost "southern gentleman" style.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:31 • by boog
 Nagesh: boog: Mastur Plan Software: boog: Q: Why are manhole covers round? I prefer my manholes uncovered.Another discomforting answer - just be sure to wink at the interviewer, for added hilarity. Manhole cover is round because the mold to make them is round. If mold to meke them is square, then you can have square or rectangle or any shape you like.+1 for a simple, straightforward answer that defeats the purpose of the question. Well done! It'd have been +2, but I had to deduct a point for spelling "make" both correctly and incorrectly in the same comment.

### Re: More Limitin', Wrong Major, and Parallel Universe Replacement

2011-11-23 12:32 • by Calli Arcale (unregistered)