# All Questions

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### Produce a secure block cipher round function (1 bit round key; 7 bit message)

We need to produce a block cipher round function with a 1 bit round key size and a 7 bit message size with the highest level of cryptographic security according to our measure of security. ...
2k views

### Rudin-Shapiro sequence

The Rudin-Shapiro sequence is a sequence of $1$s and $-1$s defined as follows: $r_n = (-1)^{u_n}$, where $u_n$ is the number of occurrences of (possibly overlapping) $11$ in the binary ...
• 48k
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### Shortest Algorithm* That Generates a Harlequin Pattern

What is the shortest sequence of moves that, from the solved state of the cube, creates a pattern that meets the following criteria: 6 colors on each face at most 2 facelets of the same color no ...
• 293
580 views

### Get the Bible verse

Write a program that accesses Project Gutenberg's KJV Bible, either from a file called pg10.txt in the working directory or in any other way that is typical for the ...
• 1,580
234 views

A loaded question is something like 'Have you stopped swearing?' in which both yes and no answers mean that I have swore, meaning it is impossible to answer the question if I haven't swore. However, ...
2k views

### Limited letter renderer: BIOPD

There have of course been challenges to render ASCII art fonts here and there. This challenge doesn't add anything to those. In contrary, it subtracts from them for a good reason. If you allow all ...
• 2,501
4k views

### German pharmacy payment

Your task is to calculate the amount you have to pay for prescribed medication at a pharmacy in Germany. The amount is simply based on the full price of the item, which will be your input. It is a ...
• 5,097
390 views

### Bingo Cards PDF

Write code to generate a PDF file containing 6 bingo cards. Winner is the one that uses the shortest code and needs no actions except for installing a library and running the code. (No Save As PDF). ...
• 175
2k views

### Golf Transmission

As in, the 5 speed transmission from the original VW Golf GTI. Print the transmission pattern in as few bytes as possible. Yes I know this isn't what it actually looks like but the GTI 5 speed shift ...
• 3,770
2k views

### Decode the date in Christmas Eve format

This is the inverse of "Encode the date in Christmas Eve format." Write a program that takes as input the string Christmas, possibly followed by ...
• 1,580
4k views

### Print ASCII building

Challenge Display to the screen or write to stdout this exactly: ...
• 167
318 views

### How many twisted corners?

Your challenge is to output the number of twisted corners given a 2x2 Rubik's Cube scramble. For the purpose of this challenge, twisted corners are defined as corners where the colour of the top/...
• 9,238
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### Monotone sequence beatitude

Provided that the input is a monotone sequence of three or more integers: Output -2 if the sequence strictly decreases. Example: [7,4,3,2] Output -1 if the ...
• 5,941
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Given two natural numbers (less than 100) as input print the sequence of intermediate results obtained when computing the sum of the two numbers using only the following operations1: ...
• 6,015
286 views

### Literate Programming in Base 26

Your task is to convert non-empty strings - between strings using the 26 letters, and programs, which are strings of bytes, where each byte has 256 possible values. You should use the same codepage ...
• 10.5k
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### Print the banned characters based on the most common characters

This is an answer-chaining post, so in this challenge every answer (except the first answer) depends on the previous answer. The goal of this challenge is to output the restricted characters. The ...
• 3,847
636 views

### Robinson Schensted correspondence

[The explanations of the algorithm come from here. I recommend reading it for a beautiful description of the algorithm.] This challenge is to implement the Robinson Schensted correspondence. Input A ...
• 2,896
228 views

### Determine if a Spider Solitaire game is stale

Let's introduce a simplified variant of the well known Spider Solitaire. From Wikipedia: The main purpose of the game is to remove all cards from the table, assembling them in the tableau before ...
• 12.4k
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### Make Code Printing X without X

The challenge is simple: write a program which takes in some non-empty string $n$ consisting of only uppercase and lowercase ASCII letters, and outputs the code for a program (in the same language) ...
• 7,111
6k views

### aaabbabbc⠀⠀⠀⠀⠀⠀

One element of the list aa, ab, ba, bb, c has been removed, and the remainder shuffled and joined with no separator. Find the missing element. For example, if the ...
• 14.8k
422 views

### Is there a shortest code to format string

Code Golf Challenge Given a string of 10 characters: 'abcdefghij' I want to format it in this pattern and print it in the console in a minimum number of characters: ...
672 views

### Produce the shortest suffix for an (almost) arbitrary string

I encountered some silly code from a game and I figured this would actually turn into a fun golfing problem, so: Given any ASCII string in the limited char range specified below. Append as few ...
• 199
1k views

### Encode the input to exclude a given character (part 1)

Your task is to write 2 functions/programs. They may share code. The first function must, given a string and a character, output a new string that does not contain that character. The second function ...
• 12.5k
609 views

### Sum of the sum of all possible subsets raised to power k

You are given an array A of non-negative integers. You can pick any non-empty subset, S from the array A. The score of a subset S is the sum of the elements in S raised to the power of K, i.e. for a ...
• 79
2k views

### Find the fairest partition of a list

Given a list of positive integers, partition the list into two sublists such that the absolute value of the difference of the sums over the two sublists is minimal. The output of the program should be ...
• 6,015
259 views

### Positions on the Pickleball Court

My doubles pickleball group often has five people. Four are playing and one is awaiting the next game. We can represent the state of the game with a string of five characters like abCde. This ...
2k views

### Sine using square root [closed]

Given input $x \in \left\{0,3,6,...,90\right\}$, output $\sin\left(x°\right)$ using integer and $+ - \times \div ( ) \sqrt{\cdot}$(square root), e.g. $\sin(45°)=\sqrt{1\div 2}$. Flexible ...
• 23.9k
1k views

### The too-short urinal problem

The well-known Urinal Protocol states that each person that takes a urinal will take the one furthest from any other taken urinal. But this fails to account for short urinals; in many cases, a person ...
• 6,903
2k views

### Seat gangs as far as possible

Imagine there are $n$ people $\{a_1, a_2, \ldots, a_n\}$ who enter a room in order and sit down in $n$ seats, arranged in a row. Each of these people belong to some gang, indicated by an integer ...
• 7,111
152 views

### Base consecutive k-frequency counter [closed]

Given a base $k$ as well as two indices (also passed in base $k$, call them $s$ and $e$) return a list containing a frequency count of all base-$k$ digits occurring between $s$ and $e$ ...
256 views

### It's Just Simple Math! [duplicate]

Task Your boss is on another crusade for 'efficiency.' He wants to encourage the use of numbers with fewer syllables, so that they're easier to discuss in meetings. If you want to take some time off ...
• 559
3k views

### Restricted Meta-Cat

Your challenge, should you choose to accept it, is to write a program in a language of your choice that, when given a string (limited to printable ASCII) as input, outputs a new program in the same ...
• 6,903
2k views

### Compute the conjugate of a partition

We will think of a partition as a sequence of non-increasing integers. For a given partition into $n_1, n_2, \dots, n_k$ with $n_1 \geq n_2 \dots n_{k-1} \geq n_k = n$ we write it out with $n_i$...
• 2,896
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