Questions tagged [reachability]
A puzzle on a discrete system where one has to decide whether a certain system state can be reached through a finite number of steps.
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Labyrinth of Teleporters
You find yourself in an empty room, with a few distinctly numbered elevated platforms on the floor; your only possession is a pebble that can easily be picked up and placed down. You step on one of ...
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Sliding balls and stars on a 4x4 grid
You are playing a game on the following 4x4 grid. It contains balls, stars, empty cells, walls (solid blue squares) and target cells (T). Each turn you can slide all the balls and all the stars into ...
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Sliding balls on a 5x5 grid
You are playing a game on the following 5x5 grid. Each turn you can slide all the orange balls into one of four directions: left, up, right or down. A ball will continue sliding along a direction ...
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Sliding balls on a 4x4 grid version 2
You are playing a game on the following 4x4 grid. Each turn you can slide all the orange balls into one of four directions: left, up, right or down. A ball will continue sliding along a direction ...
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Sliding balls on a 4x4 grid
You are playing a game on the following 4x4 grid. Each turn you can slide all the orange balls into one of four directions: left, up, right or down. A ball will continue sliding along a direction ...
- 36.3k
16
votes
1
answer
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Exterminating blobs on a grid
On an infinite square grid, some of the squares are occupied by little creatures called blobs. Cute as they are, it is your mission to exterminate all of them! You only have two methods at your ...
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Will you be the first to get free?
It is your first day in prison and you are approached by a guard having a hunch for puzzles.
He tells you that he gives every new prisoner the chance to be freed if they can present him with a version ...
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votes
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Swapping registers in an old calculator
I came up with this problem inspired by the limitations of an old non-scientific calculator I owned years ago (the two registers were the display, and an internal memory for an additional number).
We ...
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Permuting rows and columns to switch white rooks with black rooks
An adversary places eight white rooks and eight black rooks on sixteen squares of a chessboard, subject to these rules:
In any row, there must be exactly two rooks, one of each color.
In any column, ...
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Amnesiac in a ring shaped palace
Related: Turn off all lights in a ring-shaped palace
Your boss has trapped you inside a ring-shaped palace, and all you know about the palace is that there are some number* of identical rooms, each ...
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Consecutive Towers of Hanoi
Consider the following variant of the Towers of Hanoi puzzle. There are six pegs. One of the pegs has a stack of $n$ differently sized disks, sorted by size so the smallest disk is at the top. All ...
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Is it possible that the last piece the ant has eaten is the central one?
A cube of dimension $3×3×3$ is made of sugar and consists of $27$ small cubical sugar pieces arranged in the $3×3×3$ pattern. An ant is eating the sugar in such a way that it starts at one of the ...
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Is it possible (for some configuration of initial 9 flowers) to get all red flowers after finitely many years?
An isolated garden has the shape of a circle. Initially, there are 9 flowers on the circumference of the garden: 5 of the flowers are red and the other 4 are yellow. During the summer, 9 new flowers ...
- 239
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Professor Halfbrain and the sum of the digits of all divisors
Yesterday I met professor Halfbrain in the city. The professor looked tired and somewhat exhausted. He told me that he had spent his nights and days with adding up digits of divisors of positive ...
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Aatif averages numbers on the blackboard
Aatif has averaged numbers and made the final number $2$:
Averaging numbers on the blackboard
Today Aatif once again sees the numbers $ 1 , 2 , 3 , .... , 2016 $ written on the blackboard. In one ...
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