Be Excellent To Each Other

And, you know, party on. Dude.

All times are UTC [ DST ]




Reply to topic  [ 199 posts ]  Go to page 1, 2, 3, 4  Next
Author Message
 Post subject: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:05 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
I'm fairly sure we've done this before, but bugger it. I'll start with one. If you come up with the solution, you get to post your own puzzle, and so it continues!

If you come up with the answer, but don't have a puzzle to share, you can "gift" your win to the first person who has a puzzle ready to post, just to keep things moving.

NO GOOGLING. Play fair, guys!


***



There is a lightbulb (currently off) in an upstairs room. You are downstairs, standing next to a panel of three light switches, A, B and C. All of them are in the off position. One of them controls the lightbulb. The other two don't do anything. You must figure out which switch controls the bulb. You cannot see the bulb, nor can you tell if it is on or off from your position at the switches.

Rules:

1) You can only turn the lightswitches on an off. You can't whip your screwdriver out and take a peek.
2) After fiddling with the lightswitches, you can go upstairs and check the bulb ONCE.
3) You didn't bloody wire it.

So, you fiddle with the switches, you walk upstairs and check the bulb, and then you immediately decide which switch controls the bulb. How?


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:06 
User avatar
Hibernating Druid

Joined: 27th Mar, 2008
Posts: 49344
Location: Standing on your mother's Porsche
You wired it.

_________________
SD&DG Illustrated! Behance Bleep Bloop

'Not without talent but dragged down by bass turgidity'


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:07 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
I'll amend the puzzle...


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:12 
User avatar
Hibernating Druid

Joined: 27th Mar, 2008
Posts: 49344
Location: Standing on your mother's Porsche
You told the sparky how you wanted it wiring.

_________________
SD&DG Illustrated! Behance Bleep Bloop

'Not without talent but dragged down by bass turgidity'


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:15 
SupaMod
User avatar
Est. 1978

Joined: 27th Mar, 2008
Posts: 69711
Location: Your Mum
Turn on switch C, and have a lazy wank. Turn off C and turn B on. Go upstairs. If the light is on, it's B. If the light is off but the bulb is warm, it's C. If the light is off and the bulb is cold, it's A.

Note that this probably won't work in Kalmar's house.

_________________
Grim... wrote:
I wish Craster had left some girls for the rest of us.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:16 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
I googled it. Cute puzzle!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:17 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
Grim... wrote:
Turn on switch C, and have a lazy wank. Turn off C and turn B on. Go upstairs. If the light is on, it's B. If the light is off but the bulb is warm, it's C. If the light is off and the bulb is cold, it's A.

Note that this probably won't work in Kalmar's house.


In one, with a lazy wank! Your turn, sir.

It's interesting that you started with C, though, rather than A. Well, it probably is to a psychologist.


Top
 Profile  
 
 Post subject: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:18 
Awesome
User avatar
Yes

Joined: 6th Apr, 2008
Posts: 12334
Beat me by two minutes and a lazy wank Grim...!

_________________
Always proof read carefully in case you any words out


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:19 
User avatar

Joined: 31st Mar, 2008
Posts: 8655
And not one mention of me. I am disappointed.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:20 
SupaMod
User avatar
Est. 1978

Joined: 27th Mar, 2008
Posts: 69711
Location: Your Mum
What's the least number of times the hands of a clock overlap each other in a day?

Assuming the clock is working, it's just a normal clock, you're not flying through time zones, blah blah blah your all cocks

_________________
Grim... wrote:
I wish Craster had left some girls for the rest of us.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:21 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
It's like you're just bending over and presenting yourself to the grammar pedants.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:22 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
But also, I'm gonna say 22? Are we including the midnight starting position once or twice?


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:25 
SupaMod
User avatar
Est. 1978

Joined: 27th Mar, 2008
Posts: 69711
Location: Your Mum
WTB wrote:
It's like you're just bending over and presenting yourself to the grammar pedants.

:shrug:

WTB wrote:
But also, I'm gonna say 22?

And you are right to do so, sir.

_________________
Grim... wrote:
I wish Craster had left some girls for the rest of us.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:25 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
You know, I worked it out by messing around with the Windows clock, but I'm still fucked if I fully understand why it's only 22!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:26 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
Also, I'm throwing it open to anyone else who has a puzzle. I blew my load.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 22:28 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
Aha! I get it now. It's a good one, that. Simple at first glance but a real toughie if you don't have a clock handy!

edit: Hey! You deleted!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 23:16 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
This is one I was asked in a job interview once.

You have two glass balls and a 100 storey building. The balls will break if dropped from a certain height, x, but you can drop them endlessly from a height of less than x without damage.

Assuming the worst case, what's the least number of drops to be sure of determine x?

(so 1<= x <= 100. Here's a freebie: drop a ball from 1, 2, 3, and so on until it breaks. Worst case is you have to go all the way to 100, so that's 100 (worst case) drops. You can do a lot better than 100.)


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Mon Jul 23, 2012 23:33 
User avatar

Joined: 27th Mar, 2008
Posts: 14497
Man! There are so many ways to attempt that! I've no idea what the proper answer is, but you could at least half 100 by dropping a ball from the 50th floor right from the off. If it breaks, you start from 1 all the way up to 49 with the other ball. If it doesn't break, you've still got a spare ball so go up in increments of, say, 10 until it does break. Not sure how to get more efficient than that, though...

edit: Googled it. Interesting! Obviously going for 50 off the bat is a significant gamble. It could be very efficient if the ball doesn't break, but entirely inefficient if the ball breaks at 49. The proper solution is much more elegant and works 100% of the time.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 1:34 
User avatar
Time Out for Fun

Joined: 30th Mar, 2008
Posts: 5039
Location: South Shields
Go up in 2s until you break then say its one lower?


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 8:23 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
Runcle wrote:
Go up in 2s until you break then say its one lower?

So you hit 38 then 40? Now you don't know if it's 39 or 40. You can use your second ball to answer that. Worst case if it breaks on the 100th floor -- which is 51 drops.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 8:36 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
Go for the midpoint each time? Drop at 50, if it breaks, drop at 25. If it doesn't, drop at 75. Then do 13/38/63/88 as appropriate. Etc.

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 8:49 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
Craster wrote:
Go for the midpoint each time? Drop at 50, if it breaks, drop at 25. If it doesn't, drop at 75. Then do 13/38/63/88 as appropriate. Etc.
You're on the right lines. Work out your worst case number of drops.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:00 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
7, I think. Depends how you do the rounding.

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:03 
User avatar
Isn't that lovely?

Joined: 30th Mar, 2008
Posts: 11165
Location: Devon
Doctor Glyndwr wrote:
Craster wrote:
Go for the midpoint each time? Drop at 50, if it breaks, drop at 25. If it doesn't, drop at 75. Then do 13/38/63/88 as appropriate. Etc.
You're on the right lines. Work out your worst case number of drops.

What if it's 10 that it breaks at?

Then you've dropped 2 (broken at 50, broken at 25) and don't know the answer.

Malc

_________________
Where's the Kaboom? I was expecting an Earth shattering Kaboom!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:06 
User avatar
Sleepyhead

Joined: 30th Mar, 2008
Posts: 27354
Location: Kidbrooke
Start at Floor 14.

Worst case scenario is 14 drops.

Either it breaks and you start again from 1, or you go up by 13 and try again. Then repeat, each time either on the slow route of single increments or going up in a jump of one fewer floor than before.

14, 27, 39, 50, 60, 69, 77, 84, 90, 95, 99, 100

_________________
We are young despite the years
We are concern
We are hope, despite the times


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:10 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
Good work, Curio!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:15 
User avatar
Isn't that lovely?

Joined: 30th Mar, 2008
Posts: 11165
Location: Devon
You have 2 balls, 0-99 uses 2 digits, you use one ball as your 10s and 1 ball as your units.

so, drop the 1st ball on 10/20/30 until it breaks, then you use your 2nd ball to drop from the 10 before the break and increment it by 1.

So let's say the first ball breaks on 40, then you drop the 2nd ball on 31, then 32, 33 until that breaks, giving a best case of 2 and a worse case of 19

Malc

_________________
Where's the Kaboom? I was expecting an Earth shattering Kaboom!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:16 
User avatar
Isn't that lovely?

Joined: 30th Mar, 2008
Posts: 11165
Location: Devon
bah, beaten to the punch, and it was the wrong punch any way!

Malc

_________________
Where's the Kaboom? I was expecting an Earth shattering Kaboom!


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:22 
User avatar

Joined: 30th Mar, 2008
Posts: 14364
Location: Shropshire, UK
Image

Shown above are 4 men buried up to their necks in the ground. They can not move so can only look forward. Between A and B is a brick wall which can not be seen through. They know that between them are 4 hats, 2 are black and 2 are white, but they do not know which color they are wearing. In order to avoid being shot one of them must call out to the executioner the color of their hat. If they get it wrong, everyone will be shot. They are not allowed to talk to each other and have 10 minutes to fathom it out.

After 1 minute:

Question: Which one of them calls out ?

Question: Why is he 100% certain of the color of his hat ?


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:31 
User avatar
Sleepyhead

Joined: 30th Mar, 2008
Posts: 27354
Location: Kidbrooke
Person C calls the opposite of the guy in front after a minute.

_________________
We are young despite the years
We are concern
We are hope, despite the times


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:31 
User avatar

Joined: 30th Mar, 2008
Posts: 14364
Location: Shropshire, UK
Correct, but why is he 100% certain?


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:39 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
Doctor Glyndwr wrote:
Good work, Curio!


How is that better than mine, which is half as many drops unless I've worked it out wrong?

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:41 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
GazChap wrote:
Correct, but why is he 100% certain?


Because if B and C were the same, D would have already called out.

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:45 
User avatar
Heavy Metal Tough Guy

Joined: 31st Mar, 2008
Posts: 6605
Why do you hate gnomes?


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:50 
User avatar
Sleepyhead

Joined: 30th Mar, 2008
Posts: 27354
Location: Kidbrooke
Craster wrote:
Doctor Glyndwr wrote:
Good work, Curio!


How is that better than mine, which is half as many drops unless I've worked it out wrong?


As Malc said, what if it breaks at 50 AND 25. You'd fail.

_________________
We are young despite the years
We are concern
We are hope, despite the times


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:53 
User avatar

Joined: 30th Mar, 2008
Posts: 14364
Location: Shropshire, UK
Craster wrote:
GazChap wrote:
Correct, but why is he 100% certain?


Because if B and C were the same, D would have already called out.

Good-o!

That's my favourite logic puzzle, that one. People always treat the men as individuals "A can't see anything so he's fucked, B can't see anything so he's fucked, C can only see one hat so he's fucked" etc. and completely fail to take into account the teamwork aspect of it.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 9:58 
User avatar
Sleepyhead

Joined: 30th Mar, 2008
Posts: 27354
Location: Kidbrooke
I was going to give that explanation, Gaz, but we just had a fire drill!

New question!

What is next in the series:

SSS, SCC, C, SC, ?

_________________
We are young despite the years
We are concern
We are hope, despite the times


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:08 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
Curiosity wrote:
Craster wrote:
Doctor Glyndwr wrote:
Good work, Curio!


How is that better than mine, which is half as many drops unless I've worked it out wrong?


As Malc said, what if it breaks at 50 AND 25. You'd fail.


How? Take malc's example of 10 - you drop at 50, 25, 13, 7, 10. 5 drops.

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:10 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
Craster wrote:
How? Take malc's example of 10 - you drop at 50, 25, 13, 7, 10. 5 drops.

You only have two balls and you can't keep dropping them after they break because physics.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:10 
User avatar
Hibernating Druid

Joined: 27th Mar, 2008
Posts: 49344
Location: Standing on your mother's Porsche
Curiosity wrote:
I was going to give that explanation, Gaz, but we just had a fire drill!

New question!

What is next in the series:

SSS, SCC, C, SC, ?

Dark Souls.

_________________
SD&DG Illustrated! Behance Bleep Bloop

'Not without talent but dragged down by bass turgidity'


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:11 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
Doctor Glyndwr wrote:
Craster wrote:
How? Take malc's example of 10 - you drop at 50, 25, 13, 7, 10. 5 drops.

You only have two balls and you can't keep dropping them after they break because physics.


Oh. I would appear to have totally misread the question.

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:13 
User avatar

Joined: 30th Mar, 2008
Posts: 32624
Craster wrote:
Oh. I would appear to have totally misread the question.

Based on past experiences, I assumed you misunderstood physics.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:16 
SupaMod
User avatar
Est. 1978

Joined: 27th Mar, 2008
Posts: 69711
Location: Your Mum
Curiosity wrote:
I was going to give that explanation, Gaz, but we just had a fire drill!

New question!

What is next in the series:

SSS, SCC, C, SC, ?

I know this one! I'll let someone else answer, but here's a clue: Think letters.

_________________
Grim... wrote:
I wish Craster had left some girls for the rest of us.


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 10:31 
User avatar
Hibernating Druid

Joined: 27th Mar, 2008
Posts: 49344
Location: Standing on your mother's Porsche
Grim... wrote:
Curiosity wrote:
I was going to give that explanation, Gaz, but we just had a fire drill!

New question!

What is next in the series:

SSS, SCC, C, SC, ?

I know this one! I'll let someone else answer, but here's a clue: Think letters.

Doh! I was thinking it would have been a number.

_________________
SD&DG Illustrated! Behance Bleep Bloop

'Not without talent but dragged down by bass turgidity'


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 11:45 
User avatar
Ticket to Ride World Champion

Joined: 18th Apr, 2008
Posts: 11895
FC


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 11:47 
User avatar
Sleepyhead

Joined: 30th Mar, 2008
Posts: 27354
Location: Kidbrooke
Bobbyaro wrote:
FC


Incorrect.

_________________
We are young despite the years
We are concern
We are hope, despite the times


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 11:49 
SupaMod
User avatar
Commander-in-Cheese

Joined: 30th Mar, 2008
Posts: 49244
I've googled it. I would suggest that it's actually close to impossible to work out / guess the answer.

_________________
GoddessJasmine wrote:
Drunk, pulled Craster's pork, waiting for brdyime story,reading nuts. Xz


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 11:51 
User avatar
What's this bit for exactly?

Joined: 6th Dec, 2008
Posts: 880
Location: Caerdydd
SSSS

SC for lowercase
:-)


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 11:54 
User avatar
Sleepyhead

Joined: 30th Mar, 2008
Posts: 27354
Location: Kidbrooke
Mr Dom wrote:
SSSS

SC for lowercase
:-)


Correct!

_________________
We are young despite the years
We are concern
We are hope, despite the times


Top
 Profile  
 
 Post subject: Re: Brain Teasers and Logic Puzzles
PostPosted: Tue Jul 24, 2012 11:57 
User avatar
ugvm'er at heart...

Joined: 4th Mar, 2010
Posts: 22389
Craster wrote:
I've googled it. I would suggest that it's actually close to impossible to work out / guess the answer.


Indeed, without the clue I would have had no idea.


Top
 Profile  
 
Display posts from previous:  Sort by  
Reply to topic  [ 199 posts ]  Go to page 1, 2, 3, 4  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: Columbo, MaliA, PRISM and 0 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search within this thread:
You are using the 'Ted' forum. Bill doesn't really exist any more. Bogus!
Want to help out with the hosting / advertising costs? That's very nice of you.
Are you on a mobile phone? Try http://beex.co.uk/m/
RIP, Owen. RIP, MrC. RIP, Dimmers.

Powered by a very Grim... version of phpBB © 2000, 2002, 2005, 2007 phpBB Group.