Be Excellent To Each Other

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?

You wired it.

I'll amend the puzzle...

You told the sparky how you wanted it wiring.

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.

I googled it. Cute puzzle!

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.

Beat me by two minutes and a lazy wank Grim...!

And not one mention of me. I am disappointed.

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

It's like you're just bending over and presenting yourself to the grammar pedants.

But also, I'm gonna say 22? Are we including the midnight starting position once or twice?

And you are right to do so, sir.

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!

Also, I'm throwing it open to anyone else who has a puzzle. I blew my load.

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!

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.)

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.

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.

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.

7, I think. Depends how you do the rounding.

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

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

Good work, Curio!

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

bah, beaten to the punch, and it was the wrong punch any way!

Malc

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 ?

Person C calls the opposite of the guy in front after a minute.

Correct, but why is he 100% certain?

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

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

Why do you hate gnomes?

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

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.

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, ?

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.

Dark Souls.

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

Based on past experiences, I assumed you misunderstood physics.

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.

FC

Incorrect.

I've googled it. I would suggest that it's actually close to impossible to work out / guess the answer.

SSSS

SC for lowercase
:-)

Correct!

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