Questions tagged [strategy]

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

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Sliding Bolt Puzzle - fastest solution (time-wise)

This is a follow-up question for the Sliding Bolt Puzzle. If you have not solved it yet, you might want to head there first, as the extended discussion of its solution in this question will contain ...
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1answer
537 views

Optimal building strategy puzzle with airdropped mining bases

The general from Optimal Building Strategy Puzzle is in a conflict with another general. This general is from another faction with 3 major differences in his technology: Instead of the worker having ...
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3answers
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Queen chasing a knight (chess pieces)

There is a player who controls only a queen, while his opponent controls a knight. Both pieces start from opposite corners of the board. The aim is to kill the knight, without having your queen killed....
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6answers
882 views

Optimal next move in minesweeper game?

In order to solve this minesweeper game, what is the optimal next move? A description of the game can be found here: https://en.wikipedia.org/wiki/Minesweeper_(video_game) I do not have the answer ...
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4answers
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Battleship Game with only one Aircraft Carrier

Two guys are playing regular battleship game with only one Aircraft Carrier, with dimensions $5\times1$. Their table is regular $10\times10$ Battleship game grid board. One guy places his Aircraft ...
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2answers
712 views

Lots of Gold Golden Coins and a Scale

Following my previous question: Lots of Gold Stacks and a Balance Scale You are given 10 stacks, each stack consisting of N golden 10g-coins and a digital scale with perfect precision that shows ...
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3answers
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Card game rigging

You and your friend are playing a game with a deck of cards numbered 1 to N. You will first put the deck of cards in whatever order you want. Next your friend will choose an option: "A" or "B". ...
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1answer
2k views

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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5answers
1k views

The Great Houdini's awesome card guessing trick (2)

The Great Houdini is performing again! Everybody wants to see the famous magician and the magic show is sold out. Today Houdini shows the following sophisticated trick: A guy from the audience ...
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7answers
1k views

7 Numbered Balls Game

You are walking on the street and notice a guy gambling with some other guys and you start to watch. The game principle is pretty easy. There are 7 balls in a pouch and you have 3 balls to draw ...
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3answers
2k views

Reverse the order of 8 poisonous substances

8 very poisonous substances named s1 to s8 are kept in a safety room. The substances are kept in ascending order (s1,s2,s3,s4,s5,s6,s7 and s8). In the room there are 3 robots. First robot can "rotate ...
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1answer
503 views

Picking A Number Game

Alice and Bob play a game starting from Alice where Alice and Bob are supposed to write a number to the board, Then the game goes through several rounds between Alice and Bob with the rules below: ...
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4answers
525 views

Maxit negotiations

Your military junta has recently overthrown the government of Malta and taken control of the small island nation. As a way to finance your wise and just dictatorship, you have decided to threaten the ...
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1answer
665 views

I am caught when I was about to steal some candies

I am a eight years old boy, I love candies, but my mom does not want me to eat any more candies because I start to have black teeth :( but I still love candies so... Today when I was about to steal ...
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3answers
332 views

Four-in-a-line Puzzle

Disclaimer: This is an open-problem, I don't have a complete solution for this puzzle yet. We are playing a $2$-player game: you as a challenger and me as a judge. Initially, there is an empty ...
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2answers
480 views

Guess n binary digits

There's a N (1 ≤ N ≤ 1 000; N is pair) digit binary number and you have a maximum of 2050 guesses to find out which is it. With each try, you will know one of the following: You got it right (100%); ...
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6answers
1k views

Devious auction game

Saw this on TV today: A man is auctioning a real $20\$$ bill. There are a vast number of bidders. A person may make as many bids as he wants. The starting bid is $5\$$. No $2$ bids must be ...
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2answers
1k views

Getting Stuck on Purpose

Consider the following building floor plan, with a set of rooms labeled A-G and an Outside:                   ...
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2answers
613 views

Middle weight puzzle

There are 100 white and 101 black balls. All the balls have different weights. Balls of the same colour look the same. White balls are numbered from lighter to heavier (from 1 to 100). The same is ...
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3answers
844 views

Forty-six genuine and two fake coins

Inspired by this puzzle. In the country Dragonia, there are only two types of coins: genuine ones and fake ones. All genuine coins have the same weight, and all fake coins have the same weight. It is ...
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2answers
768 views

The mini-facebook puzzle

The database of mini-facebook only has space for the data of 100 participants. These 100 participants want to establish as many mini-facebook friendships among them as possible. However, mini-facebook ...
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3answers
1k views

Coin inverting game

Header and Tailer play the following game. At the beginning, the juror lays out a row of $n\ge5$ coins on the table that alternately show heads and tails, with the leftmost coin showing heads. ...
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4answers
388 views

A “Find the Path” Puzzle

I invented a puzzle, inspired by Simon Tatham's Portable Puzzle Collection. Is there anything that it could improve on? Was it too easy, or was it too hard? Anything I could add? What must I call it? ...
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5answers
402 views

Two person game, choosing an integer between 1 and 30?

Suppose two players are playing a game. The first player chose an integer, n st. $n \in \left\{ 1,\ldots ,30\right\}$. The second player picks a different one. After that, a random integer x st. $x \...
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1answer
274 views

Two players playing the SET game

The SET game works with a deck of $81$ cards. Each card contains a set of symbols with four attributes: color (red, green, purple), shading (empty, striped, or solid), shape (oval, squiggle, or ...
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3answers
2k views

Thirteen coins game

There are $13$ coins arranged in a circular fashion. Andrew and Bill play a game with these rules: Andrew starts the game A player can remove $1$ or $2$ adjacent coins from the circle during his turn....
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4answers
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How do we get those dang Illuminati?

The Illuminati just stole our office They shot JFK and have committed numerous crimes against humanity (not really) but we usually let that slide. But for stealing our offices, we have decided to ...
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4answers
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The Greedy Box (Or: Another crazy guard offering his prisoners freedom)

Two prisoners, in separate cells, are watched over by one eccentric and whimsical guard. One day he (inevitably) decides to give the prisoners a chance to earn their freedom by playing a game with ...
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1answer
513 views

Lost In Boston: How do I Get Home?

I'm posting this from my phone again because I've gotten hopelessly lost in Boston, really want to go home, and desperately need the help of some clever people on the internet. Please help me - I'm ...
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3answers
2k views

A puzzle of trust and lies, allies and spies

Here is a puzzle involving distrust and asymmetric knowledge. (It was inspired by, but not exactly following, the board game The Resistance: Avalon.) There are ten resistance fighters trying to ...
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1answer
331 views

How to deal with conjugate-pair pseudocycles when solving Sudoku

In single-solution regular Sudoku puzzles, sometimes you may encounter a combination of possible cell solutions such as: {2,7} in A1 and A7 (same row) {2,7} in A7 and B8 (same box) {2,7} in B8 and E8 ...
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4answers
419 views

Ten users, three lights but it's a chatroom

This is a variant of the classic problem of m prisoners n lights. (Example may be found here but note that the requirements are not exactly the same) The goal for you, however, is different. You want ...
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1answer
453 views

Clearing the Robot Museum

The grand opening of the Collapsible Robot Museum is just 1 week away in the robot nation of Robotia. The museum is unique because shortly after the museum closes, the building collapses into a flat ...
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2answers
361 views

16 Two Colored Line up

We have a different type of puzzle which consists of 4x4 board with numbers on it; Your task is to put numbers in the correct order as given in the diagram above. In each step, you can take one ...
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2answers
293 views

What other strategies can I use with this sudoku puzzle?

I have a sudoku puzzle that I have been doing for 270 hours. I never guess numbers and always thought that every move in sudoku had to have a logical explanation. Until the app generated this random ...
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3answers
409 views

Gettings most jewels in a square 5x5

Playing an online game I came across a small puzzle (a mini-game in game). The game is about getting jewels in a row - a player needs to get 5 in a row / column or a 5-square-diagonal. Let me show you ...
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6answers
2k views

How will Y lose the game?

X and Y are playing a game. There are eleven coins on the table and each player must pick up at least one coin but not more than five in a turn. The person picking up the last coin loses. X starts. ...
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6answers
901 views

Single-pile Nim with Three Players

Three perfectly rational logicians (Alice, Bob and a Quetzalcoatlus) are playing a game. (Charlie couldn't make it, so he asked the Quetzalcoatlus to fill in for him.) The rules are very simple: ...
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2answers
627 views

2016 coins and a balance

On the table, there is a balance with two pans. The display on the balance tells the difference between the weight in the left ban and the weight in the right pan (measured in gram). There are also $...
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2answers
961 views

Find the term which does not fit into the series given below

C4T, F10R, I20P, L43N, O90L It can be easily seen that the first letters are 3rd, 6th, 9th, 12th, 15th and the last ones are 20th, 18th, 16th, 14th, 12th. But I cannot understand the logic of numbers ...
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3answers
2k views

Is it always safe to click first in the lower lefthand corner of a Minesweeper puzzle?

I always start a Minesweeper puzzle in Windows by clicking the cell in the lower left corner. Even though I have never seen a bomb there, how sound is this strategy? Is it possible that some time in ...
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3answers
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Surviving Captain Nefarious

Captain Nefarious has captured you and two of your friends, Alice and Bob. Being a villain, he has a natural desire to monologue, so he sits you down (guarded, of course by his Largely Incompetent ...
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3answers
794 views

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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1answer
818 views

Heaps of marbles

Alice and Bob play the following game with two heaps of $10,000$ and $20,000$ marbles. Alice and Bob move alternatingly. Alice makes the first move. In every move, the active player may (i) either ...
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3answers
388 views

Writing differences on a blackboard

The numbers 25 and 36 are written on a blackboard. At each turn, a player writes on the blackboard the (positive) difference between two numbers already on the blackboard, if this number does not ...
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3answers
1k views

Sliding 10 coins to make them alternate

You have 10 coins: five heads, then five tails, all in a row. HHHHHTTTTT (H is for heads and T is for tails.) In each move, you can take two adjacent coins and ...
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3answers
565 views

The Ebbozonian coin weighing puzzle

In the country of Ebbozonia, there are only two type of coins: light coins and heavy coins. The weights of these coins satisfy the following properties: All light coins have the same weight $L$. All ...
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4answers
623 views

Higher or lower?

The game “Higher or Lower” is a simple one in which playing cards are drawn randomly from a deck, and the player has to guess whether each subsequent card will be higher or lower in value than the ...
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2answers
717 views

A generalization of Tyler Seacrest's “Three voting prisoners” puzzle

The following is a straightforward (but nonetheless not completely trivial) generalization of Tyler Seacrest's great puzzle "Three voting prisoners". There are $n\ge2$ prisoners that have a brief ...
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2answers
1k views

The Great Houdini's awesome card guessing trick (3)

The Great Houdini is performing again! Houdini has built up lots of reputation by showing his great card guessing tricks in [predecessor puzzle-1] and in [predecessor puzzle-2]. Everybody wants to see ...