Questions tagged [keys-and-locks]

For puzzles about using keys to open locks and doors.

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13
votes
5answers
871 views

How do you create a general locked-box problem?

In this question, I presented a puzzle involving seven locks, with a Grand Vizier and four slaves. But I would like to use this style of puzzle in some of my own secret-unlocking riddles, in order to ...
12
votes
4answers
4k views

The Puzzle of the Locked Box

Here's an old puzzle I found in a book once. A box has some number of locks on it. It is guarded by a Grand Vizier and four slaves, each of which hold keys to the locks. The Grand Vizier and ...
75
votes
10answers
17k views

10 Prisoners, 10 Keys, and 7 Years

One day, the warden of a prison is, like most wardens in puzzles, feeling a little bit capricious and decides that he wants to get rid of his prisoners, one way or another. He gathers all the ...
14
votes
6answers
3k views

Do you have my spare key?

I have three bicycle locks, ones like this: Because they look so much alike I etched a unique number into each lock and the same number into the keys that unlock it. Unfortunately I seem to have lost ...
20
votes
2answers
2k views

One Hundred Lockboxes of Wood and Steel

A bit beyond perceptions reach, I sometimes believe I see that life is two locked boxes, each containing the other’s key. ― Piet Hein You have one hundred lockboxes, fifty made of steel, ...
7
votes
2answers
616 views

Key and lock puzzle

The idea is to place all the yellow keys into the red locks. There is at least one guaranteed way to do this as the locks as created from the keys and then 'blurred' by adding extra gaps. Solutions ...
4
votes
2answers
509 views

Lock Optimisation

In a simple combination lock, a sequence of several digits is used as a password, with one wheel per digit. Generally, it is not possible to unlock the lock without knowing the password, but due to ...