Questions tagged [strategy]
A puzzle whose solution is a methodological plan of action for realizing a specific goal.
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Twelve balls and a scale
You are given twelve identical-looking balls and a two-sided scale. One of the balls is of a different weight, although you don't know whether it's lighter or heavier. How can you use just three ...
user88
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Which switch goes to which bulb?
You are in a room with three switches, labeled $A$, $B$, and $C$. Initially, each switch is in an off state. In an adjoining room, there are three incandescent light bulbs. Your task is to ...
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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 ...
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3
answers
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Sliding Bolt Puzzle
You are in a room with two adjacent doors locked by four sliding bolts. The bolts are movable and block only one door at a time; however, you do not know which bolt currently is blocking which door.
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answer
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Coins on a table
John and Jane are playing a game. They both go to the bank and each get 1000 euros in two-euro pieces. So each of them has 500 coins at stake. They then find a large rectangle table and decide that ...
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Dinosaur egg drop
Archeologists discover two dinosaur eggs, and you are given the chance to test the durability of these eggs (bad move on their part). Suppose that these eggs will absorb a specific amount of force ...
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Learning to Solve a River Crossing Puzzle
I have seen many variations of the following puzzle:
Once upon a time, a farmer went to the market and purchased a fox, a goose, and a bag of beans. On his way home, the farmer came to the bank of ...
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Is it possible to use one sequence of moves to solve the Rubik's cube from any position?
Is there a sequence of moves that can be repeated over and over again which can solve any legal position the Rubik's Cube? If so what is it, and if there's more than one, what's the shortest? If not, ...
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How to beat Count Dracula
Abraham Van Helsing and Jonathan Harker play a game against Count Dracula.
The three players agree on the following rules:
Count Dracula and Van Helsing enter the crypt, while Jonathan Harker ...
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The lake monster
You are on a rowboat in the middle of a large, perfectly circular lake. On the perimeter of the lake is a monster who wants to eat you, but fortunately, he can't swim. He can run (along the perimeter)...
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1 Fake Coin among N Amount of coins
You are given $N$ coins which consists of only $1$ fake coin. You also have a sensitive old-fashioned Pan Balance Scale.
You are asked to find the fake coin in totally 5 times weighing on the Pan ...
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6 Tries to Guess a Number Between 1-100
After every time you guess, you're told if you're right, too high, or too low. Is there a strategy you can use to guarantee you'll get it on your 6th attempt (or lower)?
I know a strategy to get it ...
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votes
12
answers
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Turn off all lights in a ring-shaped palace
Not a very difficult question, but one I enjoyed nonetheless and wanted to share with the community.
You are a servant in a palace. The palace is in the shape of a circle, and you do not know how ...
Oria Gruber
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3
answers
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Sink the Submarine
There is submarine somewhere on the number line. Initially (say, at midnight), it is at position $A$, and is moving $B$ units per hour to the right, where $A$ and $B$ are both integers; both $A$ and $...
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10 prisoners and 10 lists of numbers [duplicate]
10 prisoners are held captive by a cruel warden. One day he gathers them in the prison hall and tells them about a new game he wants to play:
"Tomorrow, I will assign each one of you a random ...
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20 coins on the table
Two boys , Brian and Gabe, decide to play a game.
They lay 20 coins on the table. Each player took turns taking 1, 2, or 3 coins. Whoever took the last coin won.
Brian thought if he went first, he'd ...
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votes
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The total cost of salaries in a company
Story Version (scroll for TL;DR)
It's the end of the first quarter of 2017.
This means it's the end of the 2016 fiscal year (at least in my country it is).
It's time to draw the line.
So the CEO did ...
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answers
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Clever ways to solve Mastermind?
Is there any specific way to solve Mastermind?
Apart from the first step that is pure chance, is there any way to continue based on the colors that you think are correct?
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7
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Faulty computers
You have $99$ computers in a LAN room, and you know that at least $50$ are working. The others can be faulty.
The only thing you are allowed to do is to ask computer $i$ the question "Is computer $j$ ...
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Labeling wires in a bundle
At a remote location, you just finished trenching a data cable across a large plot of land. The cable has 64 individual wires that are not color-coded or labeled.
You have a wire stripper, a simple ...
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The Expedition Into The Ancient Cave
You are a archeologist and have taken 8 of your students on a expedition trip to a ancient cave to try and find ancient treasure. After you and your team entered the cave, you travel as a group ...
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A secret polynomial
Alice has a secret polynomial $P$ with positive integer coefficients. When Bob gives Alice a positive integer $n \neq 2016$, Alice replies with the value of $P(n)$. After doing this several times, Bob ...
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answers
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The lion and the zebras
The lion plays a deadly game against a group of 100 zebras that takes place in the steppe (= an infinite plane).
The lion starts in the origin with coordinates $(0,0)$, while the 100 zebras may ...
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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 ...
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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 ...
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Strategy to beat the casino over the long haul
$A$ and $B$ are attempting to beat the casino again, and the rules are the same:
Each round, $A$, $B$, and the casino simultaneously decide to show a $0$ or a $1$. If all three numbers match, $A$ ...
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answer
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What is the strategy to solve Simon Tatham's Twiddle?
Consider the goal 3x3 position:
You must reach this position by rotating 2x2 blocks by some multiple of 90 degrees like so:
Orientation of each individual number is preserved.
What is the ...
- 9,842
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votes
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answers
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Red and Blue in the Chocolate Fountain Room
Where: Hackanoogie Prison. When: Who cares?
The Master Key Keeper had had a really good day and in a fit of insanity and niceness decided to let all the inmates to go free if they manage to carry ...
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answers
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Escaping a hungry lion you can't outrun
You are at the edge of an enormous circular arena. A hungry lion is eying you from the centre of this area. You are both capable of running at the same maximum speed, but constraint within the arena. ...
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answers
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How to survive, with statistics
You are kidnapped and your offender plays a game with you. In front of you are 2 boxes, containing a total of 50 white balls and 50 black balls. The kidnapper will pull out a ball from one of the two ...
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votes
1
answer
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Master and Slave versus Bob: hard version
Continuation of: "Sub-puzzle: Master and Slave versus Bob the Violent but Honest Psychopath" and "Master and Slave versus Bob: easy version"
The hard version is identical to the easy version (see ...
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Can the Policeman catch the Thief?
The town of Squareshire has six streets: four sides of a square and the lines joining the midpoints of opposite sides.
$\hskip2in$
A policeman is chasing a thief along these streets. If they are ...
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How can one solve a Rubik's cube without relying on guides/algorithms?
I am wondering who is able to solve Rubik's cube just by thinking without knowing the rules behind it. As far as I know the inventor Ernő Rubik was professor of architecture and he intended to help ...
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Strategy to beat the Casino
Two players, $A$ and $B$, and the Casino play a game. It involves showing zeros or ones: each player picks $0/1$ and also the Casino picks $0/1$.
If the Casino and both players $A$ and $B$ show the ...
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There are at least three Kevins on Puzzling. I plan to trap them in my labyrinth
Note: please do not edit the title! It originates in a challenge in Stack Overflow chat.
I have rounded up all ten (currently) of the Puzzling SE users named Kevin and trapped them in my labyrinth. ...
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The Devil's Brother
The 1933 movie "The Devil's Brother" (also known under the title "Fra Diavolo") takes place in the Northern Italy of the early 18th century.
Stan Laurel and Oliver Hardy play the fierce robbers ...
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30 fake coins out of 99 coins
You are given 99 coins which consists of 30 fake ones. You also have a digital balance scale with perfect precision that shows how much difference between weighs you put on. For example, if you put 10 ...
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Reunite the Stars
On an infinite plane, the Prime Star has disintegrated into four constituent stars, the North Star, the South Star, the East Star and the West Star, each traveling at a constant speed of 1 in their ...
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The Mexican Standoff
There are three cowboys in a Mexican standoff against each other, named Juan, José, and Jorge.
Juan is the straightest shooter in the West, and can hit his target 100% of the time.
José, who has a ...
user88
14
votes
3
answers
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Strategy to beat the Casino reversed
Let's consider Strategy to beat the Casino puzzle, but reverse it - fix number of losses and ask a question about amount of rounds:
Two players, A and B, and the Casino play a game. The game consists ...
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answer
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99 chips into more chips
You are at a casino in Vegas and you have earned 99 chips by playing poker!
While you are checking out a slot machine, someone comes to you and congratulates you that you have a chance to make more ...
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Dinosaur Egg Drop v2
This question is a little different and kinda follow-up version of Dinosaur Egg Drop
1- You have 100 story building and 6 Apatosaurus dinosaur eggs.
2- You have 81 story building and 3 ...
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answer
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Master and Slave versus Bob: easy version
Continuation of: "Sub-puzzle: Master and Slave versus Bob the Violent but Honest Psychopath"
Continued in: "Master and Slave versus Bob: hard version"
Previously I described a game that is played ...
- 5,118
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votes
3
answers
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Sub-puzzle: Master and Slave versus Bob the Violent but Honest Psychopath
[I created this as a sub-puzzle to "Strategy to beat the Casino reversed", that has been sitting unsolved for months. You may wish to read that puzzle first, but this is self-contained. My answer to ...
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Coin Flipping Game with the Devil
You die, and awake in Hell. Satan awaits you, and has prepared a curious game. He has arranged $n$ quarters in a line, going in the east/west direction. He placed the coins at the ends tails up, and ...
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votes
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Left coin, right coin, last coin?
In this game, all players start sitting at a round table, each with a coin in their hand.
At every turn, all players toss their coins together and put them on the table in front of them. Then each ...
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votes
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The Circular Prison of Unknown Size
You are the president of a secret society of mathematicians with $n$ members, including yourself. No one in the society knows what $n$ is. The dictator of the world, in an effort to erase mathematics ...
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lolcatz can haz ur infinit cheeseboard
This is a problem on an infinite chessboard with pieces called lolcatz. They can move like queens or knightriders, but have a strange disadvantage...
... you've never heard of knightriders? Well, ...
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Duel between the knight and the dragon
A dragon and a knight live on an island where the only sources of fresh water are a pond (containing ordinary water) and six wells, numbered 1 to 6. Each well's water is completely indistinguishable ...
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100 prisoners and a secret number
There are 100 prisoners numbered from 1 to 100. They know their own numbers. There is an interrogation room with a table and an envelope. The envelope contains a secret number - an integer chosen ...
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