Current Events > Brain puzzle

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RlP
07/15/22 8:49:49 PM
#1:


I'm bored so I'll share some random brain puzzles I remember.

If you are confident you know the answer, please use spoilers as to not ruin the puzzle for others.

You have 2 ropes of an unidentified material and a box of matches. The material has a non uniform burning rate, parts of it burn faster than others, however you know each one takes exactly 1 hour to burn from end to end. How can you measure exactly 45 minutes with the 2 ropes and box of matches?

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toreysback
07/15/22 8:50:40 PM
#2:


look at your phone

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LordFarquad1312
07/15/22 8:51:33 PM
#3:


You light both ends of one rope and one end of the other. As soon as one burns out, you light the other end of the other.

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The_X_Dawg
07/15/22 8:54:29 PM
#4:


I am not smart.
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RlP
07/15/22 9:00:08 PM
#5:


LordFarquad1312 posted...
You light both ends of one rope and one end of the other. As soon as one burns out, you light the other end of the other.

Correcto!

toreysback posted...
look at your phone

You only have the ropes and matches, you were stripped of everything else because reasons and also are in an empty room (besides you and the aforementioned items)

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RlP
07/15/22 9:00:31 PM
#6:


The_X_Dawg posted...
I am not smart.

Practice makes smart =)

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EyeWontBeFooled
07/15/22 9:16:49 PM
#7:


Moar

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RlP
07/15/22 9:24:32 PM
#8:


EyeWontBeFooled posted...
Moar

You have 2 identical robots that are separated apart by an unknown distance. You know there is a button between them (that does nothing) and the robots can only move left or right. This diagram might help:

[0.0] = robot
* = button
_ = one unit of space

____[0.0]______*_________[0.0]______

You need to command the robots in such a way that they can meet each other; however both robots will share the same instructions. If you tell them move right then both will move right at the same time and same distance.


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AvlButtslam
07/15/22 9:54:48 PM
#9:


The_X_Dawg posted...
I am not smart.
Same even after reading the solution Im just like huh

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RlP
07/15/22 9:57:48 PM
#10:


AvlButtslam posted...
Same even after reading the solution Im just like huh

You know each rope takes 1 hour. If you burn both sides of the same rope at the same time then you know it will take 30 minutes for that specific rope to be fully consumed.

Hopefully that should help understand the answer better, if not let me know and I can explain the other part of the solution.

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toreysback
07/15/22 9:58:26 PM
#11:


call the button tech to come repair the button. after all it is clearly obvious that the button is designed to get the robots to meet once it's pushed, so long as it is operative. it is clearly obvious that this one is currently inoperative

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RlP
07/15/22 10:00:40 PM
#12:


toreysback posted...
call the button tech to come repair the button. after all it is clearly obvious that the button is designed to get the robots to meet once it's pushed, so long as it is operative. it is clearly obvious that this one is currently inoperative

You are on the right track but that's not the answer. Remember you can tell the robots what to do, you dont need to bother the tech repair guy who is happily browsing GameFAQs.

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Steffenfield
07/15/22 10:35:43 PM
#13:


Place the button on the right side of the right robot as to blockade that one from moving the same as the left robot when having them both go right?

I think I said right on that far too many times.

But am I right? :)
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RlP
07/15/22 10:42:06 PM
#14:


You cannot physically move the robots or button. The button is also small enough that it wouldn't block any robots from moving. You can only give them the same order(s) and multiple orders if you want. To clarify, you can give them any order you want but they can only move left, right or do nothing.

Extra tip: The robots can be aware if they are currently stepping on the useless button or not.


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RlP
07/15/22 10:44:55 PM
#15:


Also, feel free to ask any clarifying questions on the puzzles if you think you might require more information to make it easier to come up with a solution.

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Mistere_Man
07/15/22 10:46:19 PM
#16:


RlP posted...
You have 2 identical robots that are separated apart by an unknown distance. You know there is a button between them (that does nothing) and the robots can only move left or right. This diagram might help:

[0.0] = robot
* = button
_ = one unit of space

____[0.0]______*_________[0.0]______

You need to command the robots in such a way that they can meet each other; however both robots will share the same instructions. If you tell them move right then both will move right at the same time and same distance.

https://youtu.be/BkDVXEik82o?t=132

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Steffenfield
07/15/22 11:13:27 PM
#17:


Commanding them to both go left, right, or remain motionless together, no matter how many times you do this, they will always be equally distant from their starting separation.

Something needs to impede one of the robot's progression.

Unless you're wanting us to bend space and/or time, because not even thinking in three dimensions could this be solved the way your problem is stated.
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RlP
07/16/22 1:22:01 AM
#18:


There's a solution and it's not bs like bending space time although fun theories are welcome. toreysback answer is pretty close.

Here's the key part of their comment

toreysback posted...
it is clearly obvious that the button is designed to get the robots to meet once it's pushed



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#19
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kirbyy
07/16/22 10:05:14 AM
#20:


Tell them to both move towards the button

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Steffenfield
07/16/22 10:43:46 AM
#21:


Once a robot reaches the button, smash it with a hammer.

Proceed by inputting the opposite direction until they meet.

Or perhaps turn one of the robots to initially face backwards.

I hate this puzzle.

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toreysback
07/16/22 11:57:27 AM
#22:


build a third robot - a "matchmaker" robot

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the_rowan
07/16/22 12:02:05 PM
#23:


The puzzle really doesn't give enough information to be interesting as stated. Either the robots cannot be instructed to move relative to the button and the puzzle is impossible, or they can and the instruction "move to the button" has them meet trivially.

Note that, if the robots can only process a command in the form "Move left until you are on the button" or similar, the puzzle becomes only conditionally possible, as giving a command like this without a max duration results in one of the robots getting stuck on this instruction forever, while including a max duration makes the solution not work if the button takes longer to reach than that duration.

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RlP
07/16/22 1:31:34 PM
#24:


[LFAQs-redacted-quote]


Technically you are right, this works if the robots can communicate between each other. For example robot A would need to know that robot B passed the button in order to start moving to the other side. Robot B would indeed know that they reached the button and be able to stop. I'll consider this correct since I dont think I specified whether robots could be aware of where the orher was. However what if the robots can't be aware of the other robot position nor the position of the button (unless they are literally standing on top of it?)

kirbyy posted...
Tell them to both move towards the button

Also could work the way I described so its technically correct it but see above on what robots can or cannot know if you want an extra challenge.

Steffenfield posted...
Once a robot reaches the button, smash it with a hammer.

Proceed by inputting the opposite direction until they meet.

Or perhaps turn one of the robots to initially face backwards.

I hate this puzzle.

Lmao, kudos on thinking outside the box and just turning one of them the opposite direction! That'd work. For the purpose of the puzzle, assume the robots are very heavy and you can't lift them up or move them by hand. You are almost there though: once the robot reaches the button, why do you want to smash it? What does that accomplish? You can achieve the same outcome without smashing it. Then as you mention you want to make the other proceed to the other direction somehow.

the_rowan posted...
if the robots can only process a command in the form "Move left until you are on the button" or similar, the puzzle becomes only conditionally possible, as giving a command like this without a max duration results in one of the robots getting stuck on this instruction forever, while including a max duration makes the solution not work if the button takes longer to reach than that duration.

Close, you can actually frame the instructions in such a way that the duration is unlimited yet the robot that has not reached the button isnt stuck going in the wrong direction forever.Tip: There's a reason they can move both left and right, in your solution you only use one of those options. What would you do if you cant be sure whether the button is to your left or your right? Answer: You need to somehow search for it on both sides.

CE is on the right direction, I think most of you already got the first part right and are just missing the second half of the solution.

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Ivany2008
07/16/22 2:10:22 PM
#25:


Here's a riddle:

You are stuck in a room with no windows or doors. In front of you is a table and a mirror. How do you escape the room?
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RlP
07/16/22 2:16:27 PM
#26:


Is it one of those detective rooms where the mirror is a double sided mirror? If so I guess use the table to break the mirror and escape throught it.

If not, is there anything else in the room? Like a vent so I dont die of asphyxia? How did I get into the room in the first place? What materials are the floor, ceiling, and walls?

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#27
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Steffenfield
07/16/22 2:25:36 PM
#28:


Something a bit fun and free to enjoy.

https://poki.com/en/g/the-impossible-quiz#
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Ivany2008
07/16/22 2:57:36 PM
#29:


RlP posted...
Is it one of those detective rooms where the mirror is a double sided mirror? If so I guess use the table to break the mirror and escape throught it.

If not, is there anything else in the room? Like a vent so I dont die of asphyxia? How did I get into the room in the first place? What materials are the floor, ceiling, and walls?

None of that matters in the riddle.

The Answer for those curious is this:

You look in the mirror to see what you saw
You take the saw and cut the table in half
Two halves make a whole
you jump into the hole and leave the room

Added on to that by one person was this:
After jumping through the hole you scream until your voice is hoarse
You ride away on the horse
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Steffenfield
07/16/22 3:04:54 PM
#30:


Ivany2008 posted...
None of that matters in the riddle.

The Answer for those curious is this:

You look in the mirror to see what you saw
You take the saw and cut the table in half
Two halves make a whole
you jump into the hole and leave the room

Added on to that by one person was this:
After jumping through the hole you scream until your voice is hoarse
You ride away on the horse
That answer is completely nonsensical. *lol*

Never would have even gotten the first step through solving for this.
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Ivany2008
07/16/22 3:09:46 PM
#31:


Steffenfield posted...
That answer is completely nonsensical. *lol*

Never would have even gotten the first step through solving for this.

That's why its a riddle with wordplay.
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RlP
07/16/22 3:53:04 PM
#32:


I'd never have gotten that riddle either. i did think of something like looking into the mirror and somehow being free in the mirror world.

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RlP
07/16/22 4:01:16 PM
#33:


Summary of the puzzles since there's been a couple now:

Rope answered by LordFarquad1312, bonus point if anyone can explain why that answer works.

Robots: Unanswered but Bullet_Wing, kirbyy, Steffenfield gave some good alternative answers before I clarified some of the restrictions.

Trapped in a room: No one answered it yet.

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RlP
07/16/22 4:22:03 PM
#34:


Recap for robot problem, CE is almost there so I dont want to spoil the answer. If people give up I guess I can spoil it after a couple of more guesses.

What we know we have:
  1. Robots with a button in between them
  2. Robots can move left or right
  3. Robots can know if they are stepping on the useless button.
  4. Robots must receive and follow the same instructions.
What we cant do
  1. Physically move the robots or button
  2. Robots cannot communicate with each other
  3. Robots cannot use the other robot as a reference
What we know we need to do
  1. Use the button as a reference to tell the robot(s) to stop moving.
  2. Avoid the other robot from moving to the same direction indefinitely after the first one stops moving



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Steffenfield
07/16/22 4:28:52 PM
#35:


Pull the battery out of the first robot that touches the button.

With that logic though, why not just kill the power on one of them initially?

Build a homeless shelter next to one of them, and send inputs going in that direction.

They both can't progress past that area.

Did I mention that I hate this puzzle?
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the_rowan
07/16/22 4:38:29 PM
#36:


So you can get the robots to meet like this: (assume N has an initial value greater than 0).

Move left for N seconds
Multiply N by 3 (or any value greater than 2)
Move right for N seconds
Multiply N by 3
Loop

If at any point you are on the button, stop in place and do not follow further instructions.

It's inefficient as hell but should work even if the button is arbitrarily far away.

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RlP
07/16/22 4:50:15 PM
#37:


Steffenfield posted...
Did I mention that I hate this puzzle

The puzzle loves you, you just broke their heart

the_rowan posted...
So you can get the robots to meet like this

This is close enough, so its correct! You cant tell them to move X amount of time (that's not an available instruction) but the answer is pretty much the same: You want them to oscillate: Move right 1, move left 2, move right 3, move left 4 until but stop if you are stepping on the button. Once one of the robots steps on the button they will stop moving forever, so it is only a matter of time until the second robot finds their sibling by oscillating.

Kudos to you for getting it right, it is not an easy answer. In fact it was an interview question I had to solve back in the day, it stuck with me for some reason.

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Steffenfield
07/16/22 5:07:02 PM
#38:


You phrased the riddle incorrectly.

"both robots will share the same instructions"

There was no mention at all of conditional programming for them.

At least I'm not bitter.
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RlP
07/16/22 5:34:55 PM
#39:


How would you have phrased that part to make it less ambiguous? In my mind sharing instructions is different than both doing the same the action at the same time. The instructions are the same but the outcomes can be different

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RlP
07/16/22 7:03:14 PM
#40:


New puzzle:

You are carrying 3 boxes: one with apples, one with oranges and the other with both apples and oranges. A co-worker plays a prank and labels all of the boxes incorrectly so that you dont know what is in them. For example the first box has an "apples" label, the second oranges, and the third says apples and oranges.

You cannot see inside the boxes but you can ask for a sample fruit from them. For example you could ask to get a fruit from box 1 and get an orange. What is the minimum amount of fruits you need to sample before fixing all labels?

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MedeaLysistrata
07/16/22 7:03:49 PM
#41:


RlP posted...
New puzzle:

You are carrying 3 boxes: one with apples, one with oranges and the other with both apples and oranges. A co-worker plays a prank and labels all of the boxes incorrectly so that you dont know what is in them. For example the first box has an "apples" label, the second oranges, and the third says apples and oranges.

You cannot see inside the boxes but you can ask for a sample fruit from them. For example you could ask to get a fruit from box 1 and get an orange. What is the minimum amount of fruits you need to sample before fixing all labels?
lol

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Steffenfield
07/16/22 8:16:28 PM
#42:


Circle through each of the three boxes at a time and take out a single piece of fruit.

Continue doing so until you pull a second, different fruit out of one of the boxes.

There's no minimum number of attempts due to mathematical random probabilities.
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Medussa
07/16/22 8:26:26 PM
#43:


i lovehate topics like this, because i've almost always seen the questions and know the answers. the temptation to show off is hard to keep in check, lol. but it'd be hollow.

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Ivany2008
07/16/22 8:27:51 PM
#44:


None. You don't need to sample any fruit. You can't see inside the boxes, but that doesn't stop you from reaching inside the boxes and feeling what's inside.
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ellis123
07/16/22 8:31:57 PM
#45:


Ivany2008 posted...
None. You don't need to sample any fruit. You can't see inside the boxes, but that doesn't stop you from reaching inside the boxes and feeling what's inside.
You wouldn't even need to do that. Apples and oranges do not weigh the same amount, so by carrying them in the first place you would know which was in each.

Though the minimum amount needed to be taken out of the boxes would be four if you wanted to go that route.

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the_rowan
07/16/22 8:43:17 PM
#46:


RlP posted...
New puzzle:

You are carrying 3 boxes: one with apples, one with oranges and the other with both apples and oranges. A co-worker plays a prank and labels all of the boxes incorrectly so that you dont know what is in them. For example the first box has an "apples" label, the second oranges, and the third says apples and oranges.

You cannot see inside the boxes but you can ask for a sample fruit from them. For example you could ask to get a fruit from box 1 and get an orange. What is the minimum amount of fruits you need to sample before fixing all labels?

One fruit. Take it from the one labeled "apples and oranges". Whatever you pull out is in this box.

Say you pull an apple from this box. Then "apples and oranges" contains apples. "Oranges" must contain apples and oranges, since it is mislabeled and you already know the box that contains only apples. Therefore "Apples" contains only oranges. The same logic applies if you pull an orange, just shuffling the boxes.


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Steffenfield
07/16/22 8:46:03 PM
#47:


the_rowan posted...
One fruit. Take it from the one labeled "apples and oranges". Whatever you pull out is in this box.

Say you pull an apple from this box. Then "apples and oranges" contains apples. "Oranges" must contain apples and oranges, since it is mislabeled and you already know the box that contains only apples. Therefore "Apples" contains only oranges. The same logic applies if you pull an orange, just shuffling the boxes.
Well I certainly pooched that riddle. :D
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RlP
07/16/22 8:53:24 PM
#48:


Medussa posted...
i lovehate topics like this, because i've almost always seen the questions and know the answers

Glad to see someone (partially?) likes the puzzles.

Ivany2008 posted...
None. You don't need to sample any fruit. You can't see inside the boxes, but that doesn't stop you from reaching inside the boxes and feeling what's inside.

I forgot to clarify that someone else would give you the sample, so you wouldnt be able to touch the fruit so this is technically correct.

ellis123 posted...
You wouldn't even need to do that. Apples and oranges do not weigh the same amount, so by carrying them in the first place you would know which was in each.

Interesting approach, however not all apples nor oranges weight the same. There could be 10 small oranges, 3 medium size, and 1 large in the orange box.

the_rowan posted...
One fruit

Correct. Have you seen these puzzles before? You got them pretty easily, I'm impressed.

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Medussa
07/16/22 8:56:29 PM
#49:


RlP posted...
I forgot to clarify that someone else would give you the sample, so you wouldnt be able to touch the fruit so this is technically correct.

usually this puzzle uses color to differentiate. the objects are otherwise identical.

RlP posted...
Glad to see someone (partially?) likes the puzzles.

likes. just bummed i can't really participate.

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the_rowan
07/16/22 9:08:33 PM
#50:


RlP posted...
Correct. Have you seen these puzzles before? You got them pretty easily, I'm impressed.

So I have seen some of these before like the rope one, and I think I saw the box one before as well, but didn't remember the solution. However, it's immediately clear that the only box you are guaranteed to learn information about by pulling a fruit from it is the "apples and oranges" box. If you pull an orange from the apple box, for example, you learn no new information, and this can happen infinitely many times, so it doesn't make sense for pulling from the "apple" or "orange" box to be part of the solution.

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