Questions tagged [algorithm]

A puzzle related to algorithmics (a main concept in computer science).

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17
votes
2answers
7k views

A general solution to the decanting problem? (aka jug-pouring, water-pouring)

Take a look at these two questions: - A Set of Water Jug Challenges - Pouring problem Now I'm asking for a generalised solution to that problem. I define the problem as follows: You are required ...
84
votes
7answers
18k views

Why does this solution guarantee that the prince knocks on the right door to find the princess?

I found this puzzle online: On the top floor of a castle lives a princess. The floor has 17 bedrooms arranged in a row. Each bedroom has doors connecting to the adjoining bedrooms as well as to the ...
19
votes
4answers
2k views

Checkerboard Infection

There is a dangerous bacteria, Checkerichia Coli, (or C. Coli for short) which lives in the squares of checkerboards. Squares with this bacteria living in their digestive systems are said to have "C-...
27
votes
7answers
2k views

23 Clones and Two Lightbulbs

Rise and shine, Mister Bond. James awoke to find himself yet again imprisoned by an evil genius. At least, that's what he presumed. He was alone in a room with a strange device: it consisted of a ...
12
votes
7answers
3k views

Fastest way to collect an arbitrary army

I am looking for solution of this puzzle: There is a kingdom with a square shape with sides of length 1. The castle is located at the center of the square. At the castle the king lives under the ...
18
votes
5answers
4k views

Maze Solving Robot

Archie the archeologist has discovered an Egyptian temple, and plans to send in a robot to explore it. He uncovered the ancient engineers' papyruses which explain almost everything about the temple's ...
29
votes
5answers
3k views

Switch The Knights

On a small $ 4 \times 3$ chessboard, the top row is filled with black knights and the bottom row with white knights. On each move, you may move one knight (as it moves in chess) to an unoccupied ...
20
votes
2answers
1k views

Desegregate the Knights

You are given a 3 by 3 chessboard with a knight on each corner, where the knights in the top row are black and in the bottom row are white. On each turn, you may move a knight of either color (the ...
10
votes
2answers
1k views

Let's deal with “Names in Boxes” Safely

I met a puzzle, which is basically well known 100 Prisoners' Names in Boxes , but... it has an algorithm, which gives prisoners 100% chance to survive! This is achieved by a small change in the ...
7
votes
4answers
292 views

Savage Road Signs (Part 2)

Please read part 1 or this might be confusing Since part 1, you have replaced the stolen stickers and your daughter has forgiven you. The highway ended up being a full 700km long, so you are happy ...
30
votes
8answers
2k views

Wolves and sheep

All the sheep were living peacefully in the Land of Shewo. But suddenly they were struck by a danger. A few wolves dressed up as sheep entered the territory of Shewo and started killing the sheep one ...
23
votes
7answers
5k views

Hacking an electronic keypad

You are a spy trying to break into an enemy facility. The back door is protected by an electronic keypad lock. You know that this particular lock is opened by a four digit code. Any stream of button ...
12
votes
2answers
375 views

Cubical Infection

You may remember the C. Coli bacteria, which infects checkerboard squares. There is a similar disease which plagues cubes, known as cubic lice. Once a cube gets infested with cubic lice, it will be ...
4
votes
1answer
308 views

Two knights searching for a princess in a castle

There is a castle with rooms arranged in a 3x3 square grid. The princess living in the castle sleeps in a different room each night, but always one adjacent to the one in which she slept on the ...
-4
votes
10answers
926 views

SafeCracker #3 - We've Been Blocked [closed]

Our Last Safe To Conquer Ok, team, this one might give us a little trouble. Nothing we can't handle though... let's go... This safe model is "The NevaCrak 9000" - the most secure safe there is. ...
4
votes
2answers
819 views

Counting triangle algorithm

There is a type of puzzle where one needs to count triangles in a figure, generally a large triangle full of lines which create smaller ones. One example Is there, or can someone develop ;), an ...
1
vote
1answer
841 views

The swap puzzle

The swap puzzle Place small coins heads up on the squares marked H and tails up on the squares marked T. Swap the positions of the Heads for the Tails in as few moves as possible. There are two ways ...