Logic puzzles for you!
Sep. 28th, 2012 03:07 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
blimixI wrote a puzzle today, and in correcting it, I discovered that it lends itself to a series of similar puzzles with intriguing variations. Have a crack at them yourself, and expect to see some spoilers if you view comments. I know that some of you won't be able to resist this.
Puzzle 1:
The sphinx crossed a secret chamber deep in the castle's basement, trying to keep a level head and ignore the sounds of battle coming from outside. Her friends would survive only if she could quickly find and disable their enemy's source of power. There was, she had been informed, only one path to that source. As she approached the three doors, each one in turn formed a mouth and spoke, then went silent and became again a plain, wooden door with a number on it.
The first door said, "Door two speaks truly and leads to doom."
The second door said, "Door three speaks truly and leads to power."
The third door said, "Door one lies and leads to power."
An inscription above them read, "At least one door speaks the truth."
Puzzle 2:
"Good thing they sent a sphinx to handle this," she thought, passing through the doomless door.
There followed a similar array, but this time, the inscription read, "The person who knows which door leads to power still doesn't know whether it lies."
The first door said, "Door three lies and leads to power."
The second door said, "Door one lies and leads to doom."
The third door said, "Door two speaks truly and leads to doom."
Puzzle 3:
"Cute," thought the sphinx, leaving the door open behind her. "There was a fast way and a slow way to think about that, and for my friends' sake, I'm glad I found the fast way." But the next set of doors made her pause.
The inscription read, "The person who knows how many doors lie will know which door leads to power."
The first door said, "Door two lies and leads to power."
The second door said, "Door three speaks truly and leads to power."
The third door said, "Door one speaks truly and leads to doom."
Puzzle 4:
"I'll have to use that one later," the sphinx noted as she passed through the door. "Though I can't help wondering whether by 'power' they mean 'more doors'."
The next wall displayed the inscription, "The person who can discern between truth and lies will know the door to power."
"Well, of course they will," she scoffed. "Someone who could detect lies wouldn't have to use logic here at all! What kind of clue is that?" But her friends needed her, so she approached the doors.
The first door said, "Door three lies and leads to doom."
The second door said, "Door one lies and leads to power."
The third door said, "Door two speaks truly and leads to power."
She pondered this. "Huh. Maybe I do need to consider that inscription."
Afterward:
Carefully aiming her flashlight, the sphinx flipped the circuit breakers labeled "Robot pirates" and "Weasel mind control ray". The wiring wasn't up to code anyway, so really, she was doing them a favor.
Which doors did she pass through?
Author's note (because I was asked): "And" is used formally here. So if door 4 lies, it could still tell a half-truth, like "Bunnies are fuzzy and emeralds are soft." The word "and" makes the entire sentence false if any part of it is false.
Also, yes, you can assume that one and only one door in each puzzle leads toward power, and the other two indeed lead to doom. I intend "power" and "doom" to be negations of each other, so don't bother with doors that lead to both or neither. (Save that idea for a lateral thinking puzzle set.)
Puzzle 1:
The sphinx crossed a secret chamber deep in the castle's basement, trying to keep a level head and ignore the sounds of battle coming from outside. Her friends would survive only if she could quickly find and disable their enemy's source of power. There was, she had been informed, only one path to that source. As she approached the three doors, each one in turn formed a mouth and spoke, then went silent and became again a plain, wooden door with a number on it.
The first door said, "Door two speaks truly and leads to doom."
The second door said, "Door three speaks truly and leads to power."
The third door said, "Door one lies and leads to power."
An inscription above them read, "At least one door speaks the truth."
Puzzle 2:
"Good thing they sent a sphinx to handle this," she thought, passing through the doomless door.
There followed a similar array, but this time, the inscription read, "The person who knows which door leads to power still doesn't know whether it lies."
The first door said, "Door three lies and leads to power."
The second door said, "Door one lies and leads to doom."
The third door said, "Door two speaks truly and leads to doom."
Puzzle 3:
"Cute," thought the sphinx, leaving the door open behind her. "There was a fast way and a slow way to think about that, and for my friends' sake, I'm glad I found the fast way." But the next set of doors made her pause.
The inscription read, "The person who knows how many doors lie will know which door leads to power."
The first door said, "Door two lies and leads to power."
The second door said, "Door three speaks truly and leads to power."
The third door said, "Door one speaks truly and leads to doom."
Puzzle 4:
"I'll have to use that one later," the sphinx noted as she passed through the door. "Though I can't help wondering whether by 'power' they mean 'more doors'."
The next wall displayed the inscription, "The person who can discern between truth and lies will know the door to power."
"Well, of course they will," she scoffed. "Someone who could detect lies wouldn't have to use logic here at all! What kind of clue is that?" But her friends needed her, so she approached the doors.
The first door said, "Door three lies and leads to doom."
The second door said, "Door one lies and leads to power."
The third door said, "Door two speaks truly and leads to power."
She pondered this. "Huh. Maybe I do need to consider that inscription."
Afterward:
Carefully aiming her flashlight, the sphinx flipped the circuit breakers labeled "Robot pirates" and "Weasel mind control ray". The wiring wasn't up to code anyway, so really, she was doing them a favor.
Which doors did she pass through?
Author's note (because I was asked): "And" is used formally here. So if door 4 lies, it could still tell a half-truth, like "Bunnies are fuzzy and emeralds are soft." The word "and" makes the entire sentence false if any part of it is false.
Also, yes, you can assume that one and only one door in each puzzle leads toward power, and the other two indeed lead to doom. I intend "power" and "doom" to be negations of each other, so don't bother with doors that lead to both or neither. (Save that idea for a lateral thinking puzzle set.)
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
(no subject)
Date: 2012-10-01 11:55 pm (UTC)(no subject)
Date: 2012-10-02 02:07 am (UTC)And thanks for tackling these!
(no subject)
Date: 2012-10-02 02:32 am (UTC)(no subject)
Date: 2012-10-02 03:14 am (UTC)Meanwhile, I should edit the wording of the inscription.
(no subject)
Date: 2012-10-02 01:07 pm (UTC)(no subject)
Date: 2012-10-03 03:24 am (UTC)