• Berislav (unregistered)
You are at a ravine with three others and need to cross a rickety bridge. You can cross it in one minute, the three others can cross it in two, five, and ten, respectively. A flashlight (your group has only one) is always required to cross, and only two people can cross at a time. How do cross as quickly as possible?

This one is actually quite simple:

• 1 and 2 go across.
• 1 returns with the flashlight.
• 5 and 10 go across.
• 2 returns.
• 1 and 2 go across.

For a total of 18 minutes.

• (cs) in reply to Smash King
Smash King:
You notice you forgot to reload after you killed the last idiot to make you a stupid interview question, and you have no bullets around. To top it off, the chair, desk and the box are bolted to the ground so you can't use them as weapons (probably someone had the same reaction before). Now what do you do?

After the interview, I build a device for traveling through time. I then send my mechanical cyborg back to kill the the interviewer's mother. I then send myself back in time with knowledge of how to stop the cyborg killer, and tell the mother I'm from a future where her son helps lead a rebellion against the massive cyborg army which has destroyed mankind. I then sleep with the mother, and become the unintended father of the interview. And now, you're grounded young man.

• (cs) in reply to Marc B
Marc B:
The most efficient shape for a manhole cover would be cone-shaped. That way, no matter the size of the hole, the cover would always fit.

What about the extra protrusion when covering rather small manholes, you ask? Wouldn't that hit the bottom of passing cars?

Well, that sounds more like a user problem, not an engineer problem.

I would extend the solution and use spheres. They are easier to transport (you can roll them) and they fit the manhole from every side (no problem with 'this side up')... and we could play pool on the streets using cars!

• GrahamS (unregistered) in reply to Aaron
Aaron:
And you can't have a lip on any other shape?

If it was square (for instance) then the cover would fit down the hole on the diagonal - you only need a very slight lip on a circular cover to prevent this.

Whereas on a square manhole cover that was say 100cm x 100cm the diagonal is around 141cm, so you'd need a much bigger lip.

Got it?

Oh and for the bridge one the answer is 17 (actually I think that one is a pretty good "programmer's mind" test).

• Manic Mailman (unregistered) in reply to fruey

[quote user="fruey"][quote user="Johhny Awkward"]you can't drop a round cover down a round hole[/quote] Reminds me of when I was a kid and we were playing in the storm drains in our neighborhood (a giant maze of tunnels!). When my buddy went to put the cover back on he dropped it onto the hole from about 3 feet up and it split in two and dropped right in.

How's that for thinking outside the box?

• Nick (unregistered) in reply to Chris

Precisely my solution...a tandem bike.

• Manic Mailman (unregistered)

How about fixing my quoting fubar (that'll teach me to skip the preview)...

Johhny Awkward:
you can't drop a round cover down a round hole
Reminds me of when I was a kid and we were playing in the storm drains in our neighborhood (a giant maze of tunnels!). When my buddy went to put the cover back on he dropped it onto the hole from about 3 feet up and it split in two and dropped right in.

How's that for thinking outside the box?

• (cs) in reply to Berislav
Berislav:
You are at a ravine with three others and need to cross a rickety bridge. You can cross it in one minute, the three others can cross it in two, five, and ten, respectively. A flashlight (your group has only one) is always required to cross, and only two people can cross at a time. How do cross as quickly as possible?

This one is actually quite simple:

• 1 and 2 go across.
• 1 returns with the flashlight.
• 5 and 10 go across.
• 2 returns.
• 1 and 2 go across.

For a total of 18 minutes.

If it's so simple, then why did you get it wrong? 2+1+10+2+2 = 17.

• GrahamS (unregistered)

Jeff Atwood did an CodingHorror post a while back about questions to ask at interviews. I liked his a lot better.

• soft_guy (unregistered) in reply to snoofle

I had an interview where someone asked me to estimate the number of piano tuners in the united states. We worked through it together. Afterwards he told me he asks the question to see if the person can be calm when faced with that situation, not because he cares about the answer other than that it is reasonable. He wasn't concerned about how close I got to the actual answer - I was off by quite a bit, but reasonably close for that kind of estimate. I thought he had a pretty good explanation as to why he asked the question. Some people get very angry or act weird.

The trick ones where the interviewer cares about you finding the trick are stupid. I agree.

The guy with the matrix sounds like an idiot. You don't have time in your life to waste working for such a person.

I ask two programming questions. And then there are others I think are reasonable. I usually ask something like reversing a string or atoi which is very common. Then I give them a code test similar to the one you took, but its usually something like sorting poker hands and we give them plenty of time and we let the guy demo the program if he wants to and I observe how does this guy explain what he did. Then I read the code and look to see if its well laid out. Do I want to see code like this checked into my subversion repository? And that's it other than general background and technical fit and is the guy interested in the job - is it a good match? And that sort of thing. I have been a hiring manager many times.

People have asked me to explain reference counting and multithreading, polymorphism, etc. Those questions are pretty good.

• Mister King (unregistered) in reply to Aaron
Aaron:
eric76:
The answer is that a round manhole cover won't fall back into the hole since, with the lip, it is always wider than the manhole no matter how you turn it.
And you can't have a lip on any other shape?

Manhole covers are round because the manholes are round, and the manholes are round because drills create round holes. Duh.

Manhole covers are not all round, though your theory has some credibility, in most of New England we use Triangle covers. They are used to give the worker a visual of the direction of the tunnel below. There are smaller triangles on the cover that are pointing in the direction of the flow. And to the person above me here...Manholes are not drilled. They are dug out with a back hoe and then a pre-fabbed concrete slip is placed into the ground, then burried! DUH!! :o)

• Flagger (unregistered) in reply to Bot
Bot:
I always include riddles in my interviews. The point is not to find someone who can solve riddles, the point is to find someone who can think through problems, explain what they're thinking, and ask for help when they need it. I'm looking for someone who will think about the question for awhile, explain what they're stumped on, respond well to hints, and eventually understand how to get to the answer. People who fail are those that don't try at all, refuse to explain their thought process, or give up.
Why don't you ask him an actual problem, then?
• (cs)
Given an opaque box with three light bulbs inside and three switches outside, how would you determine which switch corresponded to which bulb if the box could be opened only once and only after all the switches were permanently set?

Open the box and ask the cat (if it's still alive).

• B92 (unregistered) in reply to Flagger
Flagger:
Bot:
I always include riddles in my interviews. The point is not to find someone who can solve riddles, the point is to find someone who can think through problems, explain what they're thinking, and ask for help when they need it. I'm looking for someone who will think about the question for awhile, explain what they're stumped on, respond well to hints, and eventually understand how to get to the answer. People who fail are those that don't try at all, refuse to explain their thought process, or give up.
Why don't you ask him an actual problem, then?

In my case, it is an "actual problem" but totally irrelevant to the job. In addition to Bot's points, it helps them to be pushed way outside their comfort zone and see how they react. That's what I do daily, so it's a valid test. If I ask a network engineer "We're opening Amazon.com, how much bandwith do we need?" I'm likely to get some dissertation on TCP/IP networking. If I ask "How much jet fuel does it take to fly from NY to LA?", I get to surprise them, push them outside the comfort zone, and evaluate how they do on all of Bot's criteria. Neither the question nor the answer matter (I just made that one up), but the approach is everything.

• (cs) in reply to Worf
Worf:
fruey:
1/ Boeing : Laden or unladen? Max takeoff or max landing? Or empty?

Zero Fuel Weight? Taxi (Ramp) weight? With or without fluids?

Or the most obvious:

What's the serial number of said 747? (each one weighs differently due to many variables (amount of paint applied, amount of metal, etc). Each 747 that rolls out from Boeing weighs differently.

Hey, not fair! I only know the weight of the 747 as quoted in my childhood Top Trumps card deck.

• luctus (unregistered) in reply to fruey
fruey:
The box is of lead. Slashdot is slashdotted. Now, what do you do?
• Frenchier than thou (unregistered) in reply to Yanman.be
Yanman.be:
The light bulbs thingy is easy:

First light 1 switch for 5 minutse, so it gets warm. Turn it off Turn on the other one and open the box. First switch corresponsd to warm lightbulb. Second switch is the lit bulb. Third switch is the unlit bulb.

Almost, nearly works.... if the bulbs are perfectly insulated from the box AND the box is empty of air. In all other cases, the hot bulb will heat the adjacent bulb(s) and you are toast, especially if it is the central one.

And THAT is the problem with stupid hypothetical questions: what are the assumptions?

• Franz Kafka (unregistered) in reply to B92
B92:
While I'll conceed that the teaser is useless for figuring out if you can program, it is VERY effective in figuring out how you handle pressure and unknowns. Did you give up immediately without even trying? If so, I don't want you working for me.

Why not? If I see a task as being pointless and unrelated to anything I need to get my job done, I'll treat it as a simple diversion. You know, for fun. Once it isn't fun, I stop.

B92:
You'd be surprised how many people sit down to a simple programming task, in the language of THEIR choice, and can't even begin the solution in an hour's time. I never cared if they finished or solved the problem. Show me that you can actually program. Again, it's weeded out a lot of hackers. The worst thing you could do is argue with me about the validity of the test. Again, I wouldn't want you working for me.

That's different - give me a design question vaguely related to the job; give me a basic programming assignment. I'll go do it and hand you the result. Just don't ask me something about a bunch of guys standing in line with different colored hats and leave wondering if this is some allegory to a real problem.

• Aaron (unregistered) in reply to Yanman.be

I imagined LED light bulbs so that solution doesn't work for me... get with the times :D

• (cs)

I don't mind some of these questions. The ones that have a trick aren't so good, since they're mostly a question of asking, "Have you heard this one before?" Had one myself during my interview with Microsoft back in 2002 - they asked the weighing objects question. Surprisingly, it was the easiest possible case - 9 objects, and you know one is heavy. I answered with the two required weighings in seconds, and probably impressed the interviewer, but I had heard it before so it wasn't a test of my skill, just my memory.

On the other hand, the ones that require the interviewee to think or estimate can be helpful, even if not relevant to the job. The question about how many piano tuners are in Detroit, for example. Probably only one out of ten people will consider part-time piano tuners when coming up with an estimate...

I think this kind of question is really only useful if the interviewee doesn't have much experience; when you can't ask them about problems they've actually solved, you have to make up problems to see how they solve them - and often more important - how they explain those solutions.

One final interview question that I've never actually heard: "If you were a Jedi living here on earth, what kind of job would you get?" Might be interesting, though I'm sure most people wouldn't be completely honest. Still, it would be a more fun question than answering the same riddles about prisoners and light switches, pirates and treasure, or whatever...

• RHSeeger (unregistered) in reply to eric76
eric76:

The answer is that a round manhole cover won't fall back into the hole since, with the lip, it is always wider than the manhole no matter how you turn it.

There are two shapes that will not fall through the hole, a Rouleaux triangle being the other one.

There are actually several reasonable answers to the question of why they are round (for us, they're not in other places of the world). See the following for more details: http://www.straightdope.com/columns/read/220/why-are-manhole-covers-round

• Franz Kafka (unregistered) in reply to akatherder
akatherder:
How would you determine the weight of a Boeing 747?

With a scale.

Where are you going to find a scale that big!?

Rocketboy:
But, what if you lived in a world with no Zinc, so there was no firing pin in the gun?

Firing pins are either Titanium or hardened steel.

Smash King:
You notice you forgot to reload after you killed the last idiot to make you a stupid interview question, and you have no bullets around. To top it off, the chair, desk and the box are bolted to the ground so you can't use them as weapons (probably someone had the same reaction before). Now what do you do?

Shame on you, you should always know whether your sidearm is loaded. Oh well, bludgeon him with the pistol (it works best with steel frame weapons) and clean the blood off later.

• Joe (unregistered) in reply to Smash King
Smash King:
snoofle:
Mog:
Yanman.be:
The light bulbs thingy is easy:

First light 1 switch for 5 minutse, so it gets warm. Turn it off Turn on the other one and open the box. First switch corresponsd to warm lightbulb. Second switch is the lit bulb. Third switch is the unlit bulb.

But now one of the bulbs is broken. What would you do?

Heeeeeerrrrrrre we go again....

You pull out your trusty sidearm and shoot the other person, then open the box and throw all the switches, one at a time, to see which is which, and close the box. When the replacement person comes along, you provide the answer.

You notice you forgot to reload after you killed the last idiot to make you a stupid interview question, and you have no bullets around. To top it off, the chair, desk and the box are bolted to the ground so you can't use them as weapons (probably someone had the same reaction before). Now what do you do?

Assuming only 1 bulb is broken, turn on one switch. Wait 5 minutes. Turn on second switch and immediately open the box. If two bulbs are lit, feel the heat difference. Switches determined. If only one bulb is on, heat will tell you which it applies to. Tell the assistant to touch the filaments of the broken bulb. If he is electrocuted, it belongs to the other one switch. Otherwise, they gave you a defective box.

• Atlantys (unregistered) in reply to fruey

I always preferred the answer of "because the manhole is round". Sure, it's flippant, but those types of questions are stupid.

I remember a friend of mine had to ask those in a interview (yay for HR requirements) and asked the interviewee "how much water would fit inside the Epcot Center ball?", and the guy replied within seconds with "3 tons"

• (cs) in reply to Some dude
Some dude:
Manhole covers are round because manholes are round. Duh. :)

I was asked this exact question in an interview. It was a group interview, and the guy thought he was being clever by asking it. I was annoyed because this was the 21st century and I thought we'd got past this nonsense MS foisted on us.

My answer was something along the lines of: "When sewers were first being built, the company with round manhole covers bid the job lower than the square and rectangular manhole cover offerings. That's because it's easier to cast and machine a round shape to adequate tolerances, and so it's cheaper to manufacture the round covers. They got the job, and since then there's been lots of round sewer openings. So round covers have become entrenched (ha ha) over the years, and now it's an issue of being backward compatible."

I said this with as much "voice of reason" as I could muster, and I had a couple guys actually believing it. Like I was privy to some insider, pre-Industrial Revolution scoop with regards to modern sewer systems. In fact, we digressed into the small discussion about it.

The brain teaser dude finally said that my answer was wrong and chuckled about it. I looked him square in the eye and said that, technically, his "right" answer is wrong, too. "There are a few shapes that won't fall down their own hole, such as a certain type of triangle", I said. And then I ended with "But the round shape sure is a lot easier to make properly than a triangle with slightly curved sides, don't you think?" He was a little crestfallen.

That started them thinking again about whether I had the insider scoop on sewer systems. :-)

• Franz Kafka (unregistered) in reply to Krenn
Krenn:
I don't mind some of these questions. The ones that have a trick aren't so good, since they're mostly a question of asking, "Have you heard this one before?" Had one myself during my interview with Microsoft back in 2002 - they asked the weighing objects question. Surprisingly, it was the easiest possible case - 9 objects, and you know one is heavy. I answered with the two required weighings in seconds, and probably impressed the interviewer, but I had heard it before so it wasn't a test of my skill, just my memory.

Had one like that when interviewing this year. They acted somewhat impressed, then told the recruiter that my answer was too pat, as if I should've innovated a solution to a solved problem.

Krenn:
One final interview question that I've never actually heard: "If you were a Jedi living here on earth, what kind of job would you get?" Might be interesting, though I'm sure most people wouldn't be completely honest. Still, it would be a more fun question than answering the same riddles about prisoners and light switches, pirates and treasure, or whatever...

Hmm, Jedi or just some guy with Jedi powers? Con man, police detective, diplomat are all good choices - that's what they did in the fiction. You could also rob bank vaults and get away clean.

• bramster (unregistered) in reply to akatherder
akatherder:
How would you determine the weight of a Boeing 747?

With a scale.

Where are you going to find a scale that big!?

I'd use a tire-pressure gauge, and a string.

Use the string to measure the footprint of each tire, use the tirepressure gauge, to measure the inflation pressure of each tire, calculate the load on each tire. Add loads.

• (cs) in reply to Atlantys
Atlantys:
I remember a friend of mine had to ask those in a interview (yay for HR requirements) and asked the interviewee "how much water would fit inside the Epcot Center ball?", and the guy replied within seconds with "3 tons"

You: One gallon. Interviewer: Sorry, try again. You: Are you saying that a gallon of water wouldn't fit in the Epcot Center ball? Interviewer: ...

• Stupid (unregistered) in reply to uptaphunk

That answer is clearly wrong. If the man is tall enough to drive, he's tall enough to reach all the buttons in an elevator. The maximum height of a button on an elevator is set by law and a quick google shows that it's about 4.5 feet. If the man was shorter than 4 feet, he'd have an awfully hard time operating a car.

• Franz Kafka (unregistered) in reply to Stupid
Stupid:
That answer is clearly wrong. If the man is tall enough to drive, he's tall enough to reach all the buttons in an elevator. The maximum height of a button on an elevator is set by law and a quick google shows that it's about 4.5 feet. If the man was shorter than 4 feet, he'd have an awfully hard time operating a car.

My first thought, not ever using an umbrella, is that the stairwell got sunlight on the top 3 or 4 floors, so he got off at 7 to finish his walk in the sun. MS guys should love this, living in the rain and all.

• (cs) in reply to wee
wee:
That started them thinking again about whether I had the insider scoop on sewer systems. :-)
Don't you mean, "the inside poop on sewer systems"?
• (cs) in reply to Krenn
Krenn:
"If you were a Jedi living here on earth, what kind of job would you get?"
Jedi IS a job. He's a holy man. It's a religion, remember?
• (cs) in reply to Code Dependent
Code Dependent:
wee:
That started them thinking again about whether I had the insider scoop on sewer systems. :-)
Don't you mean, "the inside poop on sewer systems"?

Decorum prevented me from making scatological references during a job interview.

• bramster (unregistered) in reply to wee
wee:
Some dude:
Manhole covers are round because manholes are round. Duh. :)

I was asked this exact question in an interview. It was a group interview, and the guy thought he was being clever by asking it. I was annoyed because this was the 21st century and I thought we'd got past this nonsense MS foisted on us.

My answer was something along the lines of: "When sewers were first being built, the company with round manhole covers bid the job lower than the square and rectangular manhole cover offerings. That's because it's easier to cast and machine a round shape to adequate tolerances, and so it's cheaper to manufacture the round covers. They got the job, and since then there's been lots of round sewer openings. So round covers have become entrenched (ha ha) over the years, and now it's an issue of being backward compatible."

I said this with as much "voice of reason" as I could muster, and I had a couple guys actually believing it. Like I was privy to some insider, pre-Industrial Revolution scoop with regards to modern sewer systems. In fact, we digressed into the small discussion about it.

The brain teaser dude finally said that my answer was wrong and chuckled about it. I looked him square in the eye and said that, technically, his "right" answer is wrong, too. "There are a few shapes that won't fall down their own hole, such as a certain type of triangle", I said. And then I ended with "But the round shape sure is a lot easier to make properly than a triangle with slightly curved sides, don't you think?" He was a little crestfallen.

That started them thinking again about whether I had the insider scoop on sewer systems. :-)

round manhole covers are easier for the worker to roll away from the manhole. .

• (cs)
Given an opaque box with three light bulbs inside and three switches outside....

Dur.. unscrew one of the switches and pull out the wires to see what bulb is attached. Lather, rinse repeat. Reassemble. Now you really know!

Airplane one
Get a set of metal shears and a tabletop scale. Chop the airplane apart until you get bits that don't overweigh the scale. Add up the totals of all the millions of bits.
Bridge
1 minute total for me to snag the flashlight and cross. Screw the rest of those slow slackers.
• (cs) in reply to Atlantys

Interviewer: "How much water would fit inside the Epcot Center ball?" Interviewee: "I dunno off the top of my head, but I can tell you how many holes it takes to fill the Albert Hall."

• Anon (unregistered)

I'd run the Boeing through an industrial shredder then weight all the manageable boxes of pieces that come out. Then again I mostly just like the idea of watching a large airplane go through such a process. And no I don't care if it has fuel in it or not.

snoofle:
Separately, on another interview a while back, the guy asked me to write a program to display the numbers from 1-100 in a printed matrix, along with some other info. Then he lets me at his computer to write the program. And leaves the room while I do it (don't get me started on this one). No biggie. He gave me an hour. I finished in 5 minutes. I even put a nice little header on it to indicate what each column meant. The guy runs the program and pipes the output directly through wc -l and tells me it's wrong because the line count is wrong. I tell him to just run it without piping it. He sees the header and says "But I didn't tell you to print out a header". At that point, I tell him I'm not interested in working for someone who so myopically micromanages, and walk out.

I need to start asking that question so I can weed out people like you. Specifications exist for a reason, such as preventing problems when output is piped into another program that doesn’t expect a header. I’m sure the team will be really happy when their system doesn’t work (or worse, gives wrong outputs) because someone idiot didn’t follow the agreed upon specifications. I’m sure they’ll be even happier when they need to waste a couple hours tracking down what is causing it.

• (cs) in reply to Berislav

1 goes first giving 10 a piggy back ride (1 - min), once to the other side 2 gives 5 a piggy back ride (2-min)

3 min total.

Why do 1 and 2 need to return to the other side? Couldn't they just stand at the other side and shine the flashlight back across?

If it takes you only 1 minute to cross the bridge can't be in that bad of shape or very long. The flashlight shined from the other side should be fine.

Berislav:
You are at a ravine with three others and need to cross a rickety bridge. You can cross it in one minute, the three others can cross it in two, five, and ten, respectively. A flashlight (your group has only one) is always required to cross, and only two people can cross at a time. How do cross as quickly as possible?

This one is actually quite simple:

• 1 and 2 go across.
• 1 returns with the flashlight.
• 5 and 10 go across.
• 2 returns.
• 1 and 2 go across.

For a total of 18 minutes.

• Buckwheat469 (unregistered) in reply to Aaron

eric76 is correct. A square manhole cover - even with a lip - CAN fall through a square manhole if it's turned diagonally. This is simple Trig. It also applies to anything with more than 3 edges (a triangle will not fall through but it won't have much to hold it). The only shape that can't fall through more than half is a circle.

• Tom (unregistered)

I've been at MS since '95, a manager for most of that time. In my experience it was around 2000 that recruiting started assertively discouraging us from asking brainteasers. If you're still getting those in an MS interview then your interviewer is an old-timer who thinks they're too cool to try new things, or else a youngster who was taught by such an old-timer. The only dated examples I see in the comments above are from 1990 and 2001 so hopefully those interviewers are either no longer here or have figured out a better way to interview.

• Rich (unregistered) in reply to Aaron
Aaron:
I imagined LED light bulbs
LEDs cannot reasonably be described as "bulbs".
• (cs) in reply to Anon
Anon:
snoofle:
I had the opportunity of interviewing...

Wow! Kind of a douche bag aren't you? Guess the interview question did their job.

Not at all - when I interview someone for a technical role, I can usually tell by their approach (laughter/posture) to the question whether or not they know what they're talking about - without even getting to the answer. I ask questions relevant to the persons' ability to do the job at hand, as well as general subject knowledge. I try not to waste peoples' time.

The point is that I am interviewing the interviewer in the same way as s/he is interviewing me. If they fail, I tell them why and cut it short so not to waste their or (mostly) my time beyond that point.

• Rich (unregistered) in reply to Anon
Anonymous twit:
I need to start asking that question so I can weed out people like you. Specifications exist for a reason, such as preventing problems when output is piped into another program that doesn’t expect a header. I’m sure the team will be really happy when their system doesn’t work (or worse, gives wrong outputs) because someone idiot didn’t follow the agreed upon specifications. I’m sure they’ll be even happier when they need to waste a couple hours tracking down what is causing it.
The quoted specification was "display the numbers from 1-100 in a printed matrix, along with some other info".

Specifying "the output should be N lines long" after the fact amounts to scope creep; and who'd want to work for a company with such sloppy standards?

• Richard (unregistered) in reply to soft_guy
soft_guy:
He wasn't concerned about how close I got to the actual answer - I was off by quite a bit, but reasonably close for that kind of estimate. I thought he had a pretty good explanation as to why he asked the question. Some people get very angry or act weird.

More to the point, it also tells the interviewer if your estimates are realistic.

One question that I enjoyed was estimating the weight of a 747 as a range. You're explicitly allowed to give any size range you want. Its amazing how many people totally overestimate their ability and give a much smaller range than is realistic. If you don't know, your estimate should reflect that.

• kokorozashi (unregistered) in reply to B92
B92:
While I'll conceed that the teaser is useless for figuring out if you can program, it is VERY effective in figuring out how you handle pressure and unknowns.
From my perspective, it only tests for how badly the person needs a job. Good people don't need to work anywhere in particular if they don't want to. Interviews are just as much about the company convincing good people they want the company. Silly riddles annoy good people.
B92:
Did you give up immediately without even trying? If so, I don't want you working for me.
I don't just give up; I walk. I don't want to work for you. You probably have a dress code, too.
• fruey (unregistered) in reply to luctus
luctus:
fruey:
The box is of lead. Slashdot is slashdotted. Now, what do you do?

Man if Slashdot slashdotted itself, I'd be straight to kuro5hin, thedailywtf and fark to laugh about it...

• redacted (unregistered) in reply to eric76

@eric76 -

The answer is that a round manhole cover won't fall back into the hole since, with the lip, it is always wider than the manhole no matter how you turn it.

You can actually come up with an infinite number of shapes that fit that description... As long as you're not restricted to flat shapes that are the same on both sides, there's no reason it has to be round. ;) If you assume two flat "shapes" sandwiched on top of one another, only the bottom one need to match the hole. The top one can be anything (square bottom, bigger square top; round bottom, octagonal top; etc).

There's no such thing as a "right" answer. Only one that's less "wrong" than the current alternatives. (Obama 2008?)

• tino (unregistered) in reply to akatherder

LOLZ!

• (cs) in reply to Buckwheat469
Buckwheat469:
eric76 is correct. A square manhole cover - even with a lip - CAN fall through a square manhole if it's turned diagonally. This is simple Trig. It also applies to anything with more than 3 edges (a triangle will not fall through but it won't have much to hold it). The only shape that can't fall through more than half is a circle.

You fail. A triangle will fall through if turned upright. The distance from center of one side to opposite point is less than the length of a side. Therefore if you turn the triangle cover up on end and drop it down the edge of the hole it will fit and fall through.

The triangle that will not fall through is a special triangle that has curved sides, but only if those curved sides cause the distance from center of edge to opposite corner to be equal or greater than the length of a side. This is true for any shape with curved sides.

• (cs) in reply to Anon
Anon:
I'd run the Boeing through an industrial shredder then weight all the manageable boxes of pieces that come out. Then again I mostly just like the idea of watching a large airplane go through such a process. And no I don't care if it has fuel in it or not.
snoofle:
Separately, on another interview a while back, the guy asked me to write a program to display the numbers from 1-100 in a printed matrix, along with some other info. Then he lets me at his computer to write the program. And leaves the room while I do it (don't get me started on this one). No biggie. He gave me an hour. I finished in 5 minutes. I even put a nice little header on it to indicate what each column meant. The guy runs the program and pipes the output directly through wc -l and tells me it's wrong because the line count is wrong. I tell him to just run it without piping it. He sees the header and says "But I didn't tell you to print out a header". At that point, I tell him I'm not interested in working for someone who so myopically micromanages, and walk out.

I need to start asking that question so I can weed out people like you. Specifications exist for a reason, such as preventing problems when output is piped into another program that doesn’t expect a header. I’m sure the team will be really happy when their system doesn’t work (or worse, gives wrong outputs) because someone idiot didn’t follow the agreed upon specifications. I’m sure they’ll be even happier when they need to waste a couple hours tracking down what is causing it.

Actually, the spec-issue doesn't really come into play on this one - it was explained to me as a simple test to see if I could handle a doubly nested loop. No piping, no filtering, no interaction with other apps. If he wants to change the use of the application from stand alone to pipe-filter, then he has to change the requirements. I simple took some initiative to make the output pretty. Some people appreciate that.

The point is that specs, especially vague ones, go both ways. In this case, a duck is just a duck.