Raine's Logic Puzzle #1

[Raine]

You trapped in a dark room, featureless except for 8 doors labelled from 1 to 8. A voice from a speaker overhead says that only 1 of the doors lead to safety, the other 7 lead to death. He offers you a hint however. He says that he'll give 3 chances to pick as many doors as you like, and he will tell you if the correct door is among your choices. 

 

x = the door is not among them

o = the door is among them

 

Ex: Pick doors 1, 2, 4, and 5. (x)

Ex: Pick door 7 (x)

Ex: Pick doors 1, 2, 3, 4, 5, 6, 7, and 8 (o)

 

What should your three selections be in order to ensure that you're 100% certain of the correct door?

 

BONUS: Assume the voice wouldn't answer your selections until you gave all three selections first. AKA, You can no longer use the answers from one pick to help select your next pick. What would your three selections be in this case? 

 

EDIT: I'll post the solution at 11 p.m. Central tonight. 

 

EDIT: This appears to be too easy, since there are a few solutions. I'm adding a HARD Mode with a more difficult answer but still completely possible. 

 

PLEASE SPOILER YOUR ANSWERS OR MAKE DIFFICULT TO READ~ THANK YOU!

 

[spoiler=Answer]

The easy version has quite a few answers but the easiest is to take advantage of the fact that 8 is 2^3, so you can half the result every time until you're reduced to one answer.

 

For the hard version, it comes down to the logic that you can assign numbers to solutions. Pick numbers so that:

All 3 guesses have one of the same unique numbers (1 possible solution)

Guesses 1 & 2 share one unique number 

Guesses 2 & 3 share one unique number

Guesses 3 & 1 share one unique number (3 - Each has a unique solution now)

A unique number in Guess 1

A unique number in Guess 2

A unique number in Guess 3 (3 - Each has a unique solution now)

Answer is in none of the guesses (Last possible solution)

 

Each case holds only one possible number for the answer, what that number is arbitrary so long as it's within the range of 1-8 and unique within the cases above.

 

[Partangle the Candle Jangler]

Pick 1 2 3 4 5 (or any 5 but this is the most convenient) then you know it's either there or 6 7 8.

 

If it's in 1-5: Pick any 3 of those numbers, now you're down to a 3 or a 2. If it's a 2 just pick whatever and you'll know. If it's a 3 pick 2 of them and you'll have a 50/50 shot at it and that's good enough for me because funk you disembodied voice.

 

If it's 6-8, just pick any 2 and then 1 of the 2 that remain and you have it.

 

When I started typing this I thought it worked but now I see that there's a scenario where it fails so kms I might try again but probably not I'll post this anyway because I must be seen to try.

[Raine]

Pick 1 2 3 4 5 (or any 5 but this is the most convenient) then you know it's either there or 6 7 8.

 

If it's in 1-5: Pick any 3 of those numbers, now you're down to a 3 or a 2. If it's a 2 just pick whatever and you'll know. If it's a 3 pick 2 of them and you'll have a 50/50 shot at it and that's good enough for me because f*** you disembodied voice.

 

If it's 6-8, just pick any 2 and then 1 of the 2 that remain and you have it.

 

When I started typing this I thought it worked but now I see that there's a scenario where it fails so kms I might try again but probably not I'll post this anyway because I must be seen to try.

 

You're close-ish, it's not perfect but if you're in a pinch it's better than enny-mennie-miny-mo. I like the effort.

[~~~~]

[spoiler=my solution]start by picking 4 doors and halve the groups each time, following where you can deduce the o group is.

 

[mitchermitcher]

[spoiler=pfft fine i'll spoiler as well]1. doors 1 to 4

2a. (if 1 got o) doors 1 and 2

2b.(if 1 got x) doors 5 and 6

3a. (if 1 got o, regardless of 2a's result) doors 1 and 3

3b. (if 1 got x, regardless of 2b's result) doors 5 and 7

 

first step determines which half its in

 

second step(if first step got an o) determines which half of the first half it's in. third step will determine for sure which of the first 4 it's in.

 

if first step gets an x, version b determines which of 5, 6, and 7 it'll be in.

[LordCowCowCowCowCowCowCowCow]

Moo, moo moo. Moo Moo Moo. Moo.

[Raine]

I've added a BONUS rule to the question since people seem to having an easy time with it so far. New Game+, Hard Mode activate! 

 

For completing the BONUS question correctly, you will win the admiration of your peers! 

[Ryusei the Morning Star]

1. doors 1 to 4

2a. (if 1 got o) doors 1 and 2

2b.(if 1 got x) doors 5 and 6

3a. (if 1 got o, regardless of 2a's result) doors 1 and 3

3b. (if 1 got x, regardless of 2b's result) doors 5 and 7

 

first step determines which half its in

 

second step(if first step got an o) determines which half of the first half it's in. third step will determine for sure which of the first 4 it's in.

 

if first step gets an x, version b determines which of 5, 6, and 7 it'll be in.

Damn Mitcher, thanks for the Ninja

[Raine]

Damn Mitcher, thanks for the Ninja

 

Go for the hard mode! You can beat Mitcher!

 

 

1. doors 1 to 4

2a. (if 1 got o) doors 1 and 2

2b.(if 1 got x) doors 5 and 6

3a. (if 1 got o, regardless of 2a's result) doors 1 and 3

3b. (if 1 got x, regardless of 2b's result) doors 5 and 7

 

first step determines which half its in

 

second step(if first step got an o) determines which half of the first half it's in. third step will determine for sure which of the first 4 it's in

 

if first step gets an x, version b determines which of 5, 6, and 7 it'll be in.

 

Please spoil or color to make hard to read

[Aix]

• 1234
• 1357
• 1256

[mitchermitcher]

[spoiler=spoilerz]hard mode ver

 

1. 1, 3, 5, 6

2. 1, 2, 4, 6

3. 1, 3, 4

 

If all 3 gets x then it's naturally 7.

 

If all 3 gets o then it's 1.

 

If 1 and 2 gets o then it's 6.

 

If 1 and 3 gets o then it's 3.

 

If 2 alone gets o then it's 2.

 

If 2 and 3 gets o then it's 4.

 

If 1 alone gets o then it's 5.

[Ryusei the Morning Star]

Aren't there 8 doors or am I missing something

hard mode ver

 

1. 1, 3, 5, 6

2. 1, 2, 4, 6

3. 1, 3, 4

 

If all 3 gets x then it's naturally 7.

 

If all 3 gets o then it's 1.

 

If 1 and 2 gets o then it's 6.

 

If 1 and 3 gets o then it's 3.

 

If 2 alone gets o then it's 2.

 

If 2 and 3 gets o then it's 4.

 

If 1 alone gets o then it's 5.

[mitchermitcher]

Aren't there 8 doors or am I missing something

...well f***

 

somewhere along the way i made the misassumption its 8 7

 

f*** im so embarassed now

 

brb kms

[Ryusei the Morning Star]

...well f***

 

somewhere along the way i made the misassumption its 8 7

 

f*** im so embarassed now

 

brb kms

You're on the right track I think though

[~~~~]

Aren't there 8 doors or am I missing something

yes, latency failed the hard mode. this is how you actually do it

 

 

[spoiler=hard mode solution]

 

• 1, 2, 3, 4
• 1, 2, 5, 6
• 1, 3, 5, 7

 

 

 

edit: funk you aix, the only other logical person on ycm

[Aix]

Hard Mode Plus Ultra: There are 8 solutions to hard mode excluding permutations.

 

EDIT: actually that's easy to realize once you figure out hard mode.

[Raine]

Hard Mode Plus Ultra: There are 8 solutions to hard mode.

 

Absolutely true, but it's just arbitrarily switching numbers around. People just naturally start at one, I guess. They're all the same solution.  

[Ryusei the Morning Star]

[spoiler=?]

1257

1536

1647

 

If all three are O then 1

 

If just 1 then 2

 

if just 2 then 3

 

if just 3 then 4

 

if none then 8

 

if one and 3 then 7

 

if one and 2 then 5

 

if 2 and 3 then 6

 

 

I hate you all

 

Ain bigger challenge

 

doors have to be consecutive in each set

[Aix]

Absolutely true, but it's just arbitrarily switching numbers around. People just naturally start at one, I guess. They're all the same solution.  

wait actually looking at winter's solution, there are more

[~British Soul~]

[spoiler=Solution (1 of many solutions no less)]

1234

1256

1357

 

 

 

EDIT: funking ninjas.

[Ryusei the Morning Star]

[spoiler=method]I just went from 1 door in all

 

1 in none

 

3 in 2

 

3 in 1

 

 

 

 

Someone can do combinatoix magic on that and find out how many different solutions you could find

 

Is consecutive impossible?

[Raine]

wait actually looking at winter's solution, there are more

 

I know the general solution, I'll post it up at 11 as I said. 

[Ryusei the Morning Star]

[spoiler=method]I just went from 1 door in all

 

1 in none

 

3 in 2

 

3 in 1

 

 

 

 

Someone can do combinatoix magic on that and find out how many different solutions you could find

 

 

I know the general solution, I'll post it up at 11 as I said. 

Another challenge ples

 

Consecutive seems impossible with an even number of doors

 

I could be wrong tho

[~~~~]

[spoiler=Solution (1 of many solutions no less)]

1234

1256

1357

 

 

 

EDIT: f***ing ninjas.

at least someone else has good taste and is systematic

[Raine]

Another challenge ples

 

Consecutive seems impossible with an even number of doors

 

I could be wrong tho

 

I have another puzzle ready for tomorrow afternoon, wait for that one. It's a less-number based.