# Tagged Questions

Binary is the base 2 number system. Use this tag for challenges involving base 2.

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### Given a truth table, output a Stackylogic program that satisfies it

Stackylogic is a programming language I made up in a previous challenge: Run Stackylogic. Read that post for full details and examples, but here is how it works paraphrased: Stackylogic takes 0's ...
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### Run Stackylogic

Stackylogic is a logic-based programming language I made up that take in 0's and 1's for input and outputs a single 0 or 1 upon completion. A Stackylogic program consists of lines that can only ...
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### Bit-Reversal Permutations

Your goal is to create a function or a program to reverse the bits in a range of integers given an integer n. In other words, you want to find the bit-reversal permutation of a range of 2n items, zero-...
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### Swap bits with their neighbours

Task description Given an integer, swap its (2k–1)-th and 2k-th least significant bits for all integers k > 0. This is sequence A057300 in the OEIS. (The number is assumed to have “...
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### What's the Binary Time?

What's the Binary Time? Everybody knows what the normal time is. It's up there in the top-right (or wherever you put it) of your screen. But a question people rarely seem to ask themselves is this: ...
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### Mean bits: an average challenge

Given an integer N >= 1, output the mean number of bits in an integer from 0 to N - 1 Specification The output can be calculated as the sum of the number of bits in the binary representation of ...
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### Find the shortest variable length encoding [duplicate]

There is an algorithm, which, given the probabilities of certain outcomes, returns the optimal variable length encoding. Say we have a five character alphabet, with these letter probabilites: A | 0....
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### Decompose binary into alternating subsequences

This was inspired by Problem 13 - Non-Repeating Binary of HP CodeWars' recent competition. Let's take a random decimal number, say 727429805944311 and look at its binary representation: ...
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### Sum of Binary Substrings

This challenge is simple, given a decimal number, convert to binary, and calculate the sum of the sub-strings of the binary number, whose length is shorter than the original number. Here is an example:...
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### When will I have a binary car?

I noticed that my car's odometer was at 101101 when I got to work today. Which is a cool number because it's binary (and a palindrome, but that's not important). Now, I want to know when the next time ...
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### Model a probability table using 15-bit fixed probabilities

A histogram is an array of integers that counts the number of times a symbol occurs. For example, for the string "aaabbbabbdebabbbebebdbaaabbabaaaaeebeaabaaba" a histogram is a: 18, b: 18, c: 0, d: 2, ...
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### Shortest binary number in range

Given two arbitrarily precise decimal numbers 0 ≤ x < y ≤ 1, compute the shortest (in digits) binary number b such that x ≤ b < y. Output the binary digits of b after the binary ...
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### Preparing a multiple choice test

Introduction Note: this is not some kind of method to encourage cheating. As Cᴏɴᴏʀ O'Bʀɪᴇɴ already said, studying is the best solution for passing a test :3. Consider the following answers to the ...
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### 1+1 = 10, 1+2 = 3

Write a function or program than can do simple arithmetic (addition, subtraction, multiplication and division) in both base 10 and base 2. The function will take a mathematical expression as input, ...
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### I-Ching pair binary computer

Introduction I Ching is an ancient divination text and the oldest of the Chinese classics. It uses a type of divination called cleromancy, which produces apparently random numbers. The basic unit of ...
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### Binary Run-Length Encoding [duplicate]

Overview Run-length encoding — sequences in which the same data value occurs in many consecutive data elements are stored as a single data value and count When using run-length encoding: Input: ...
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### Compute the Binary Sierpinski Triangle Sequence

The Binary Sierpinski Triangle sequence is the sequence of numbers whose binary representations give the rows of the Binary Sierpinski Triangle, which is given by starting with a 1 in an infinite row ...
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### Write out the Thue-Morse sequence

There's quite a few challenges on this site that ask you to print out a sequence, and this is no exception. (The following explanation of the sequence for this challenge assumes the symbols in the ...
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### Parenthifiable Binary Numbers

If you express some positive integer in binary with no leading zeros and replace every 1 with a ( and every 0 with a ), then will all the parentheses match? In most cases they won't. For example, 9 ...
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### Simplify binary

Challenge Given a binary number as input through any means, "simplify" the number using a full program or a function. Input [binary] binary is a number in binary that is over 0. Output Take ...
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### Counting +1 primes

Define that the natural number p is a +1 prime of the natural number n if p is a prime number and the standard binary representation (i.e., without leading zeroes) of p can be obtained by adding (i.e.,...
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### Reverse and Invert a String

Reverse and Invert a String Challenge In this challenge. You'll be writing a program which will output or return the input, reversed and inverted. First, each character should be converted to its ...
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### Symmetric boolean functions as Zhegalkin polynomials

Let 𝔹 = ℤ2 = {0, 1} be the set of booleans. A symmetric boolean function in n arguments is a function fS : 𝔹n ↦ 𝔹 that checks if the number of its true arguments is in S, i. e. a ...
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### Biplex: an important useless operator

Input A list of between 1 and 255 positive integers (inclusive), each in the range 1 to 232 - 1 (inclusive). Your input format does not need to be identical to the test cases. Input without leading ...
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### Numbers with multiple runs of ones

Task Find the set of numbers such that the binary representation contains two or more runs of 1 separated by at least one 0. For example, the for the numbers that are 4 bits long: 0 0000 (...
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### Koopa Shell Sequence

In various Super Mario games green and red Koopa Troopa shells can slide frictionlessly on flat surfaces and destroy brick blocks that are in their way. When a shell hits a brick block the block ...
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### Counting cycles in a folding and squashing process

In chaos theory, the horseshoe map is an example of how chaos arises in a simple process of folding and squashing. It goes like this: take an imaginary piece of dough, fold it, and finally squash it ...
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### Generate the Temple Skyline Sequence

Consider the following process: Take some non-negative integer N. e.g. N = 571 Express it in binary with no leading zeroes. (Zero itself is the only exception, becoming 0.) e.g. 571 = 1000111011 ...
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### 16-bit binary grid

Given any unsigned 16 bit integer, convert its decimal form (i.e., base-10) number into a 4x4 ASCII grid of its bits, with the most-significant bit (MSB) at the top left, least-significant bit (LSB) ...
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### Print a table of numbers in decimal and 2**i bases

Computers live by binary. All programmers know binary. But the 2**x bases are often neglected as non-practical, while they have beautiful relations to binary. To show you one example of such a ...
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### Generate ordered binary combinations without repetitions [closed]

Challenge Write the shortest program that receives two signed integers n and i and for each i between 1 and 2^n - 1 returns the next ordered permutation based on the binary representation of the ...
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### Toggle, Print, Repeat

This challenge is loosely inspired by the unimplemented esolang Pada. Consider an array of 8 bits, all initialised to zero. We'll introduce a very minimalistic instruction set to print arbitrary ...
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### Binary Images of Triangle Counts

My challenges tend to be a little bit hard and unattractive. So here something easy and fun. Alcuin's sequence Alcuin's sequence A(n) is defined by counting triangles. A(n) is the number of ...
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### Nameless to Brainf**k converter

This is inspired by the Brainf*** to tinyBF converter challenge. Brainf**k (which will be henceforth referred to as BF) is a well-known estoric programming language, so I won't go over it too much ...
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### Find the next 1-sparse binary number

A positive integer N is K-sparse if there are at least K 0s between any two consecutive 1s in its binary representation. So, the number 1010101 is 1-sparse whereas 101101 is not. Your task is to ...
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### Count the number of ones in unsigned 16 bit integer

Write some statement(s) which will count the number of ones in an unsigned sixteen bit integer. For example, if a variable s = 1337, then set ones to 6 because 1337 as a sixteen bit binary number is ...
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### Binary encryption

This is based on xkcd #153. Make a program or named function which takes 2 parameters, each of which is a string or a list or array of bytes or characters. The second parameter will only contain ...
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### String to Binary

This is a code golf challenge. Just like the title says, write a program to covert a string of ascii characters into binary. For example: "Hello World!" should turn into 1001000 1100101 1101100 ...
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### Convert numbers to binary… but you're allowed to use twos as well

Based on the "binary, but with twos" notation mentioned in this numberphile video, write a function that takes a single number as input and outputs all variations of that number in a "binary" system ...
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### Find the simplest value between two values

Goal Your goal is to find the simplest value in an open interval. In other words, given two values a,b with a<b, output the simplest x with a<x<b. This is a code golf, so fewest bytes wins. ...
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### Convert a string of binary characters to the ASCII equivalents

Take a string of binary characters separated by a space, and convert it to an ASCII string. For example... 1001000 1100101 1101100 1101100 1101111 100000 1010111 1101111 1110010 1101100 1100100 ...
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### Give me the Gray Code list of bit width n

The Gray Code is a sequence of binary numbers of bitwidth n where successive numbers differ only in one bit (see example output). Reference Example input: 3 Example output: 000 001 011 010 110 ...
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### Make a regex that matches certain binary numbers [closed]

Your task is to create a regular expression that matches most binary numbers with an even number of 0s and an odd number of 1s (e.g. "101100011"). The full criteria for the regex are: matches 90% ...
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### math with bitwise operators

objective write a program that can perform addition, subtraction, multiplication, and division, using only bit-wise operators, by bit-wise operators i mean the equivalent of JavaScript &, |, ^, ~,...
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### change two bits by using only bitwise operations [closed]

try to write shortest possible variant of logic which converts binary input by this table: 00 -> 00 01 -> 10 10 -> 01 11 -> 11 You can use only bitwise and bitshift operations. I ...
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### Bitwise Operators in Brainfuck

Your task is to create one brainfuck program for each of the following binary operators. Each program should take one or two 8-bit numbers (A and B) from input and calculate the specified operation: ...
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### Convert from binary to unary in 7x7 Manufactoria

In the game manufactoria, take in a binary number and output that number of red pieces. The catch? The board-size is only 7x7: Here's the manufactoria code for the problem: http://pleasingfungus.com/...
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### Generating Binary shapes

How could we generate shapes or images using binary? I got to messing around trying to create something that looked matrix like and got to thinking, wouldn't a great CodeGolf be to see who can make ...