Questions tagged [strategy]

A puzzle whose solution is a methodological plan of action for realizing a specific goal.

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1answer
500 views

What will be the last Sudoku number to be filled?

When I am completing a Sudoku puzzle, there are always two last numbers to fill. Maybe it is just my puzzle solving approach or maybe it is inherent to Sudoku. I got wondering, would everyone who ...
5
votes
3answers
287 views

Dots and Boxes Part 2- Best Move in Given Position

This is a follow-up to my first Dots and Boxes question. It is just a little bit harder than the first one. Each one I post will be a bit harder than the previous one, and they will all be from games ...
5
votes
2answers
213 views

Arranging a long line of cards

Annie has a very long line of cards, numbered from 1 to $n$, such that every odd card is face-up and every even card is face-down. The only way she can modify the line is by taking any segment of ...
5
votes
1answer
279 views

Find k defective balls out of n balls

There are $n$ balls out of which $k$ are defective, where $k<n/2$. All defective balls have the same weight $w$, and all non-defective balls have the same weight $v$ with $v<w$. Determine all ...
5
votes
3answers
326 views

Strategy game on a blackboard

Adam and Bob play a game on a blackboard. A number $n>1$ is initially written on the board, and alternately they replace the number $k$ currently written with one of these: A) A positive divisor ...
5
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2answers
5k views

Is there an algorithm for the Rubik's 360?

Is there an algorithm to help me solve the Rubik's 360? Usually I just do it at random, but I rarely succeed.
5
votes
1answer
204 views

Answered it badly…on purpose?

Teacher: You got a 0. Miles Morales: Is that...failed? Teacher: Listen. If you answer all questions on a multiple choice test randomly, you would get a 25%. This means the only way for you to ...
4
votes
2answers
811 views

Five Card Magic Trick with $N$ card Deck

Last week, I saw a magic show, and was the volunteer for climactic act. The magician introduced this act by talking about the Fitch-Cheney card trick, but then explained that she was going to do an ...
4
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5answers
1k views

Coin flipping game

An $8\times8$ checkerboard is filled with two-sided coins (that are blue on one side and red on the other side). The following picture shows three examples of a cross (multiplication sign): the five ...
4
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6answers
821 views

Best strategy to get all heads/tails from three coins

Your friend has 3 fair coins: a dime, a nickel, and a quarter. She places them on a table behind you. She can arrange then in any pattern of heads and tails as long as they are not all the same. You ...
4
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2answers
257 views

How many nodes in the network?

I don't actually have a solution in mind for these, but it seemed puzzly enough to bring to the table. Seems as though someone must have come up with this before, but if so, I couldn't find it when I ...
4
votes
3answers
545 views

Dr. G's Interesting Theorem on Playing Cards

Dr. G has spent his last weekend with analyzing $n$ number of cards which are numbered from $1$ to $n$. He has a fair shuffling machine for his cards and while playing and drawing some cards, he uses ...
4
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3answers
5k views

Is there any way to 'trap' my opponent on Connect Four?

I am trying to find out if there are any 'optimal' moves in the game, so as to trap my enemy to put his pawns in the place where I need them
4
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1answer
172 views

Turn based Number game

You and a friend take turns saying positive integers greater than one. You can't say a number that is a multiple of previous numbers or a sum of multiples of previous numbers. For example, if A says 3 ...
4
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2answers
762 views

Clock puzzle using 3 hands [duplicate]

I'm quite familiar with "clock puzzles", but only when the puzzle is such that all 3 hands start at 12:00. I recently tried this one: Over a 12 hour period, how often are AT LEAST 2 of the 3 hands of ...
4
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4answers
324 views

Limited functions calculator

There's a calculator with 10 functions exp, square, sin, cos, tan and their inverses. We need to convert 0 to 1 to 2 to 3 to -3. Note: Addition, subtraction, multiplication and division are not there
4
votes
1answer
582 views

Which one is the lightest marble?

There are 8 marbles that one of them is lighter than the others, and all other seven marbles have the same weight. There is a balance scale that you can use it twice or once. Is there any way to find ...
4
votes
1answer
204 views

Find the fake bar in 2 weighing [duplicate]

You are given 8 equal sized bars of silver labeled a to h. You know for a fact one of them is fake, and the only measurable difference is weight. However you do not know if the fake bar is heavier or ...
4
votes
1answer
342 views

Fake and genuine coins

There are 14 coins, numerated from 1 to 14, and presented as an evidence at the court. The first 7 are fake coins, and others are genuine coins. Fake coins have all the same weight and they are ...
4
votes
2answers
206 views

Rearranging Frogs [duplicate]

This is a small puzzle that I saw a lot as a kid but surprisingly haven't found on this site. Enjoy! You have six frogs arranged on seven lily pads in a line: three male frogs facing right on the ...
4
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3answers
342 views

How many subset intersections do you require?

Alice chooses a subset S of {A,B,C,D,E}. Bob makes a guess of any subset T and Alice tells him the number of elements in S$\cap$T. Bob has to continue making guesses until he can exactly determine S....
4
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1answer
285 views

Variant to Minesweeper

The following game is a variant of minesweeper: There is a 7 by 7 grid of squares. Each square either has a skull or a number indicating the number of squares containing skulls surrounding that ...
4
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2answers
435 views

The Lazy worker and the Punctual Boss

Before we start, idea blatantly stolen from this puzzle Tom has found another job, with another Boss who always arrives at the same time on weekdays. This boss, however, has a different policy. If ...
4
votes
1answer
320 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
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2answers
279 views

100 prisoners' names in boxes, against smart warden

My question, which I do not know the answer to, concerns the classic 100 prisoners and 100 boxes puzzle, summarized below. The solution to this assumes the names are placed in boxes randomly, and gets ...
4
votes
1answer
446 views

Are there basic weighing puzzles requiring adaptive strategies?

Let us define a basic weighing puzzle as such: There are <number> identical balls, except one weighs <more/less/a different amount than the others> A balance scale may be used to weigh two ...
4
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2answers
2k views

When do missionaries and cannibals problems have solutions?

In the Missionaries and Cannibals problem: Three missionaries and three cannibals must cross a river using a boat which can carry at most two people, under the constraint that, for both banks, ...
4
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2answers
116 views

12 balls 1 scale with 4 groups

So, we all know the famous 12 balls 1 scale riddle. It has been here repeated many times, however, the provided solutions always start with splitting the twelve balls into three groups of four. This ...
4
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1answer
273 views

Practical Strategy to beat the casino over the long haul [duplicate]

This is another iteration of beat the casino. That question did not require a practical, implementable strategy, whereas this one does. The rules are the same and I list them below. However, the OP ...
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2answers
1k views

Coin division puzzle [duplicate]

You are blind and sitting at a table with 100 coins on it. You know exactly 50 coins are showing heads and the rest tails, and you can tell by feel where the coins are, but you are unable to see or ...
3
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4answers
2k views

10 friends play a number game

You and 9 friends are playing a game, is there a way to force a win, if so, how, if not, what is the most optimal strategy? Gameplay: Each player can have a turn, or if he/she wishes, 2 turns. Each ...
3
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3answers
528 views

Get together to-get-her ;)

You are going to meet your school friends after four years. You are very excited about it. You have planned to gift everyone a chocolate. On the day of get-together you meet everyone and feel happy ...
3
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5answers
1k views

Dominating Furbles

This question was previously from the Haselbauer - Dickheiser Test For Exceptional Intelligence, a test that was previously available on the website www.highiqosociety.com, but was removed several ...
3
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2answers
821 views

Put the colours back in order

Background I wrote up a web-based sketchpad that lets the user pick from a series of colours, and tracks the recently selected colours for ease of use. I randomly had this idea as a personal puzzle, ...
3
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3answers
671 views

Battleship- Part 2

Mason is improving at the game Battleship. He's got this current game in the bag, or so he thinks. His opponent is Richard, whose method for placing his ships is completely random. Each side has 5 ...
3
votes
3answers
326 views

Rock-paper-scissors

Sheldon, Leonard and Wolowitz play a sizzling game of rock-paper-scissors for three players. In every round, each player simultaneously shows one of the three shapes. Rock beats scissors, scissors ...
3
votes
3answers
586 views

A variation of the poisoned bottle problem

Old story. The King has received X=950 bottles of wine, exactly one of which is poisoned enough to kill a man exactly 24 hours after ingestion. The King wants to feed some N prisoners some mix of the ...
3
votes
2answers
156 views

Stakes on a table [duplicate]

Two men sat at a square table, each with a very large number of stakes. They had entered a contest of wits, or so they called it. The winner of the contest would be the last person to place a stake ...
3
votes
3answers
1k views

The duck and the wolf [duplicate]

This is quite a famous one, I think, but hopefully not too famous. The phrasing is loosely taken from here. A duck finds itself alone in the centre of a round pond. On the edge of the pond stands a ...
3
votes
1answer
808 views

$\verb|Eight Circles|$

An entry in Fortnightly Topic Challenge #37: Rare and Endangered 1 Materials Pencil; Eraser; Blank A4 sheet of paper; and A ruler (also to use as a straightedge). Puzzle: Draw a square with a side-...
3
votes
2answers
699 views

Strategy for getting out of Hedge maze?

I often wonder: suppose I wake up one day and find myself in a maze of Hedges, like the one in "The Shining", what is the best strategy to get out of it? We can assume we have sunlight or a torch if ...
3
votes
1answer
131 views

Space saving dish washing

There are some stacks of dishes on the left side of the sink. There aren't any on the right side. A larger dish can never go on top of a smaller dish (this is valid for all stacks on both left and ...
3
votes
4answers
348 views

Classic 2 Guards But With 3 Doors Instead

So the rules are almost the same : You get to ask just one question to whichever guard you want to (just 1 guard; asking both guards is not allowed) There are 2 guards, one tells the truth and ...
3
votes
3answers
613 views

Monopoly Game Show: Is there a winning strategy?

We had left the TV on after the news finished and on came the Monopoly Millionaire's Club. I had no knowledge of its existence and watched some out of curiosity. The particular game in question was No ...
3
votes
1answer
200 views

$n$ buttons on a table

A generalization of Four buttons on a table: In a certain room there is a rotating round table, with 4 symmetrically located indistinguishable buttons. Each button can be either ”on” or ”off”, ...
3
votes
3answers
188 views

Optimal number of weightings in marble problem

Consider $N$ pieces of marble. The pieces of marble look identical to one another. One of the pieces is heavier than the other. In other words, out of the $N$ pieces, $N-1$ have the same weight and $1$...
3
votes
2answers
349 views

Perfect strategy for the 2nd player in 'The coins on a table game'

I've just seen this and looked at the duplicate post it directs me to. I'm interested in a point raised in one of the comments in the answer, although it wasn't resolved in that question. It is ...
3
votes
1answer
153 views

Lattice hopping

A bunny is hopping around the plane. She must land on the following $25$ points on the main diagonal (multiples of 4): $(4, 4)$, $(8, 8)$, $(12, 12)$, $\ldots,$ $(100, 100)$, (The bunny can land ...
3
votes
2answers
937 views

Game against the Devil

While browsing through S.E you notice a spider crawl right out from under your keyboard! Startled, you twitch your hand and left clicked your mouse. You look up in shock as you notice that you just ...
3
votes
1answer
257 views

Another variation of the game of Nim

Two players set several piles of chips. The piles are arranged in a row from left to right. By turns each player takes one chip from one of the piles and adds at will as many chips as he/she wishes (...