# Questions tagged [algorithm]

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

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127 views

### Rolling dice in a box

A box containing identical dice that were arranged to have same orientation has a missing die at the center (see figure). The dice moves to the free space for they can change orientation and ...
351 views

### Infection (Information Dissemination) Puzzle

There are 2020 people in a room. One person has COVID. After each minute, each person $\mathrm{P}$ is paired with some other person $\mathrm{Q}$ who was never paired with $\mathrm{P}$ before, and they ...
89 views

### Minimise battle time in Monster's Den

So there is this excellent flash game, Monster's Den. In order to make a high score, I must complete many battles..this question is about battles with the Legendary Monsters. The target is to reduce ...
94 views

### Robot's Step, Step, Sent Back!

So there is this robot. Its origin is at (0, 0), index 0. Each pair of coordinates will have same numbers for x and y. How the robot moves is this: ...
224 views

### A robot moving on a grid

In the spirit the question I propose the puzzle: A robot is placed on a vertex of a grid. At each move the robot must take three steps along the edge of the grid. After each step the robot must turn ...
208 views

### A robot visiting every edge of a 4x4 grid

This is a harder version of this puzzle: A robot visiting every edge of a 3x3 grid A robot is placed on the top-left vertex of a 4x4 grid. At each move the robot can take one step (up, down, left or ...
237 views

### A robot visiting every edge of a 3x3 grid

A robot is placed on the top-left vertex of a 3x3 grid. At each move the robot can take one step (up, down, left or right) along the edge of the grid to the adjacent vertex, but he cannot go outside ...
446 views

### Find Local Maximum in an Integer Sequence

An element of an integer sequence is called a local maximum if it is not smaller than all its neighbors. E.g., all local maximums of the following sequence are highlighted. Consider an integer ...
191 views

### Based on 9-trains puzzle

Based on this problem, we have got some algorithms that can sort the 9 train cars in a given specific arrangement. But say if the 9 train cars are given in any-arrangement? Say ABC ABC ABC ...
130 views

### demystify and paint me!

To demystify me, look and say. Then paint me not with colors but with array. ...
173 views

### Missing number in a set of four segment circles

This is a puzzle posted on a social networking site that I have been trying hard since yesterday to solve: My approach has been to find out a mathematical function with the numbers in the yellow, ...
497 views

### GameDev: stuck with first puzzle design, would love resources to study from or algorithm suggestions!

First time posting here and I'm really, really hoping this is the community I've been looking for. I'm developing a game, right now I'm in the middle of designing levels as the core mechanics have ...
111 views

### Has Connect Four been solved on arbitrary board sizes?

Victor Allis in his program VICTOR used his algorithm for six by seven connect four, his algorithm has proven to give a sure win. Is it possible to have similar algorithm for x by y board?
189 views

### Cutting a Rectangular Board

There is an $m \times n$ rectangular board drawn on a graph paper. You need to cut it into $mn$ $1 \times 1$ squares by straight cuts along the grid lines. You are allowed to stack several pieces ...
187 views

### Minimum number of flips required to turn a sequence into alternating A and Bs

You are given this sequence composed of the characters A and B: A B B B A B B A A B A A B A A B A B A A A B B A B B B A At ...
143 views

### Oriented Rubiks Cube 4x4 re-arrange center pieces

There are a lot solutions for oriented 3x3. They rotate all center pieces. I'm trying to solve oriented 4x4 with GabbasSoft Cube Demo. Luckily blue and green ...
239 views

### An $n$-sided polygon with area $n$

Here is a $10$-sided polygon which area is $23$ (i.e. it contains exactly 23 unit squares). Can you draw a polygon with: $6$ sides and area $6$? $8$ sides and area $8$? $12$ sides and area $12$? ...
757 views

### Shift and Sort the Sequence [closed]

Given a permutation of integers 1 through N, we need to determine whether it is possible to sort this list in an increasing order by following certain conditions. The conditions imposed are : We are ...
301 views

### Algorithm for creating a “Dot” logic maze

I've been looking at Robert Abbott's logic mazes, in particular his Dot maze, and I'm trying to understand how they can be constructed so I can write an algorithm to do this automatically for ...
321 views

### The Genius Bank Robber

StackVille Bank & Trust - Robbed! The Robbery The bank is being robbed. There are millions in cash in the vault. The lone robber takes the manager to the safe and demands he opens it. The manager ...
164 views

### The Balls of Death

You have nightmares about a pool ball with the number 1 on it, and an empty box. Why? Immortality Imagine, if you will, we are 5000 years into the future. Medicine has evolved and we now are immortal -...
343 views

### The Marble Game

Johnny vs. Vinny As brothers, these two are competitive in every aspect of life. Just check out some of my other puzzles, and you'll see my brothers in action. Today is a classic Marble Battle! The ...
2k views

### Two Cannons - A Beginner's Physics Puzzle

Standoff Let's say we have two cannons aimed directly at one another ( as my horrible attempt shown in the image ). The Angles The cannon on top is aiming down towards the one on bottom right, and ...
10k views

### How to programmatically solve math puzzle

I have this puzzle and I want to solve by code. I wrote simple code trying to brute force but it fail in one condition https://dotnetfiddle.net/cJyu3w Anyone know of a link or source how to solve ...
121 views

### Determine a polynomial with nonnegative integer coefficients with minimum queries

A friend of us makes up a polynomial with nonnegative integer coefficients. Our task is to find it out with a minimum number of queries. For each query we give him a nonnegative integer $L$ and he ...
1k views

### Stacking pancakes for your wife

You are cooking pancakes for your lovely wife. You want to sort the pancakes such that they increase in diameter as you move from the top to the bottom of the stack. The only operation you can perform ...
267 views

### Two of 18 coins are counterfeit

There are $n=18$ coins, and we know exactly $2$ of them are counterfeit. All counterfeit coins differ from normal coins in weight, but otherwise their weight is not known. They can be heavier or ...
465 views

### Move all the stones into a single cell of a 3x4 grid

A 3x4 grid contains a heavy stone in each cell. Walking from a cell to an adjacent cell (horizontally or vertically) without any stones requires 1 second. Moving one stone from a cell to an adjacent ...
2k views

### Emoji primes - what's the smallest positive integer this doesn't work for?

Driven by a silly conversation at work, here's the puzzle. Slack allows users to send emoji as a reaction to a message. Emoji are listed left to right in chronological order of reaction, and 'stacks' ...
109 views

### Reapply *some* stickers on scrambled cube

I have this weird cube which have some pieces printed on the plastic and some are detachable. The cube was scrambled not solved and it fell on the floor being cheap cube almost all detachable faces ...
138 views

### Looking for an old Rubiks cube algorithm

I learnt rubiks cube before the YouTube days from a blog. I do not find the algorithm anymore online but it is something like White cross White corners (except one) Second layer corners (except one) ...
240 views

### Brute-force solver for Gear Octahedron - flawed method?

I am working on a program to brute-force a LanLan Gear Octahedron I bought second-hand (and scrambled). I have no background in "cubing" and just fancied solving the problem. The structure comprises ...
2k views

### Worst way to solve Rubik's in one algorithm

If you apply the same algorithm over and over again the cube will be solved. I want to know what algorithm is the worst one (the one with the longest cycle) I have found RU (cycle of 60 times) I have ...
289 views

### Heavy-duty computing challenge ā maximum-density word packing

Caution: This is a challenge for computers only. Humans are advised to stand well clear of the protective safety cage. There may be CPUs on fire before it's over. Introduction Nothing makes a ...
2k views

### 2 Person Same Number Verification

Alice and Beth both receive a random integer from 1 through 10, inclusive. They only know the number that they are given. The two of them want to come up with an algorithm to check that their ...
335 views

Leuks is the land of light bulbs, where the bulbs are leading a peaceful life, with no humans at all. Presently there are 100 residents . (Of course, they all are light bulbs!). Let $a_{1}, a_{2}, . . ... 2answers 2k views ### Three knights searching for a princess in a castle There is a castle with rooms arranged in a 4x4 square grid. The princess living in the castle sleeps in a different room each night, but always one adjacent to the one in which she slept on the ... 1answer 351 views ### Two knights searching for a princess in a castle There is a castle with rooms arranged in a 3x3 square grid. The princess living in the castle sleeps in a different room each night, but always one adjacent to the one in which she slept on the ... 1answer 70 views ### Arranging people to be in a group with every other person at least once There are 12 people. These people start in 4 groups - each with 3 people. They swap groups 4 times, so they are in a total of 5 groups. Is it possible for each person to be in a group with every other ... 2answers 179 views ### Hunting for treasure in 1-d grid [duplicate] In a castle, there are N rooms in a line. Each room has a door to the two neighbouring rooms (or the one neighbouring room, for the rooms at either end). A treasure is hidden in one of the rooms. ... 1answer 466 views ### Cube Scrambling Take a normal 3x3 rubiks cube (the Classic unmodded cube). I know the WCA method for scrambling is to pick a random (valid) cube state and calculate a sequence of moves to go from solved to that state,... 2answers 285 views ### Minimize sum of guesses to win lottery Ten boxes are given with$a_1,a_2,a_3,a_4,a_5 ......a_{10}$number of balls in them respectively .These boxes are randomly ordered but$a_1,a_2 .....a_{10}$is told.We can arbitrary select a box and ... 2answers 194 views ### How to find number of times sequence element$1$is approached and from where? Consider a sequence$1,-1,-1,-1,-1,-1,...,-1$. Start at the first element and move down the sequence according to the following rules: 1) If you jump from a$-1$to another$-1$, turn the latter into ... 4answers 314 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 ... 2answers 1k views ### Finding numbers having exactly two distinct digits We have$10^K$road signs (numbered 0 through$10^Kā1$). For each valid$i$, the sign with number$i$has the integer$i$written on one side and$10^Kāiā1$written on the other side. We need to ... 1answer 2k views ### Finding Round Integer An integer is round if it is greater than$0$and the sum of its digits in decimal representation is a multiple of$10$. Find an optimal procedure to compute the$N^\text{th}$smallest round integer. ... 1answer 249 views ###$4\times4\times4\$ Rubiks cube Top Layer Issue

The only way i am able to solve is to jumble the whole cube again. If you know the way to solve pls give images or algorithm.
296 views

### The CompuTaria Quest - A young Wizard's journey

Once Upon A Time In A Land FAR, FAR Away... Our adventure begins in the enchanted land called "CompuTaria". You are, "Binaryian" a 3rd year Wizard In Training. Today began like any other day - you ...