Questions tagged [algorithm]
A puzzle related to algorithms (a main concept in computer science). Puzzles may ask for an algorithm as an answer or require the analysis of a given algorithm.
156
questions
10
votes
5answers
2k views
What's the optimal strategy for Wordle?
Wordle is a game by Josh Wardle in which you try to guess a 5-letter word in at most six attempts. After each guess, the letters which are not in the word are highlighted in grey, the letters which ...
1
vote
1answer
158 views
How can the princess escape the prince?
This is the story of the sister of the princess in this puzzle. I will shamelessly copy-paste some parts of this post. I have no reference to give for this version as I adapted a Computer Science ...
5
votes
4answers
330 views
Algorithm to make two scrambled Rubik's cubes be exactly the same on all faces
There are millions of Rubik's cube combinations possible. If I have two 3×3 Rubik's cubes and both are scrambled, I want to make one scrambled cube exactly the same as the other without solving them. ...
4
votes
1answer
113 views
Copy that solution
This copy machine program prints
the solution to a well-known puzzle.
Explanation of the syntax will follow.
What solution will be printed for which
well-known puzzle?
EXECUTION CODE
.--> ...
1
vote
1answer
166 views
Find the hidden message in... this grid
(So I made this puzzle, and I wanted it to be fun rather than difficult! I hope it’s original enough)
Given a 5x5 grid as input, here’s an algorithm:
randomly select any 3x3 grid within the 5x5 grid
...
10
votes
2answers
646 views
Two dimensional Mastermind
You have probably played the classic game of Mastermind with 4 pegs and 6 colours. It turns out that the codebreaker can always find the pattern in 5 moves or fewer.
Now consider the 2D version of the ...
12
votes
1answer
755 views
Transform each square of a chessboard to zero
Each square of an 8x8 chessboard is marked with a positive integer.
The integers can be changed according to the following two rules:
(1) all integers in a row are doubled
(2) all integers in a column ...
4
votes
2answers
258 views
All possible locations of a robot going from $(x,y)$ to $(x+y, y)$ or $(x,x+y)$ [closed]
Suppose I had a little robot on the coordinate grid that moves according to the following rule. If it's at the point $(x,y)$, it can move to either $(x+y,y)$ or $(x,x+y)$. If the robot starts at the ...
1
vote
1answer
119 views
Reverse Engineer Chess Software Calculations
TLDR Just the Puzzle
Given a number n and a weight w the function f will result in a weighted number r as follows.
f(n, w) = r
n can be a number from 0 to 200
w can be a number from -100 to 100 (...
4
votes
0answers
69 views
Find the strategy: How to order without knowing [duplicate]
Imagine: You have a group of people in a room that is completely dark. Half of the group has red t-shirts and the other half blue t-shirts. The group gets told to think about a strategy to solve the ...
-4
votes
1answer
118 views
A simple two-operation calculator. How to obtain any natural number from any other?
Imagine that you possess a very simple electronic calculator. It has a screen and ten buttons from 0 to 9 to enter natural decimal numbers (positive integers). However, it can perform just two unary ...
2
votes
1answer
134 views
Is it possible to solve the Cube in a Cube in a Cube in a Cube state using its own algorithm on a 4x4?
So, I got curious if I could solve from the cube in a cube in a cube in a cube position to the solved state just using its own algorithm. This is the one I was using:
B' 2R2 2L2 U2 2R2 2L2 B F2 R U' ...
3
votes
0answers
215 views
The New York Time's "Letter Boxed" Puzzle (spoiler)
WARNING: I solved this puzzle and posted a solution below. I'm posting this more for muse.
Hello! I don't know if anyone's enjoyed this puzzle on The New York Times website, but I find it rather fun. ...
4
votes
1answer
153 views
Constant puzzle
A constant is hiding behind this puzzle, can you tell which?
4 $\rightarrow$ 2 $\rightarrow$ 1 $\rightarrow$ 1 $\rightarrow$ 1 $\rightarrow$ $\dots$
? $\rightarrow$ ? $\rightarrow$ ? $\rightarrow$ $\...
7
votes
0answers
179 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 ...
12
votes
1answer
374 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 ...
1
vote
1answer
115 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 ...
2
votes
1answer
276 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 ...
3
votes
1answer
1k 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 ...
2
votes
1answer
3k 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 ...
12
votes
3answers
1k 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 bolded.
3, * 4 *, 2, 1, * 3 *, 2, * 8 *, ...
2
votes
1answer
216 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
...
3
votes
1answer
133 views
demystify and paint me!
To demystify me, look and say.
Then paint me not with colors but with array.
...
2
votes
2answers
265 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, ...
13
votes
1answer
545 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 ...
6
votes
1answer
144 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?
4
votes
1answer
226 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 ...
4
votes
2answers
203 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 ...
4
votes
2answers
863 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 ...
9
votes
5answers
268 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 $12$?
...
5
votes
1answer
781 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 ...
7
votes
3answers
539 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 ...
4
votes
2answers
354 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 ...
6
votes
2answers
173 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 -...
3
votes
2answers
364 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 ...
11
votes
2answers
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 ...
5
votes
1answer
15k views
Programmatically solving a math puzzle with four unknowns and four equations
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
How can I solve such problems?
5
votes
2answers
142 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 ...
8
votes
2answers
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 ...
1
vote
3answers
486 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 ...
14
votes
4answers
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' ...
3
votes
1answer
148 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 ...
2
votes
1answer
171 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)
...
5
votes
1answer
304 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 ...
11
votes
1answer
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 ...
7
votes
1answer
310 views
Heavy-duty computing challenge — 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 ...
13
votes
12answers
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 ...
5
votes
3answers
348 views
land of light bulbs
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}, . . ...
13
votes
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 in the ...
4
votes
1answer
381 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 ...