# Questions tagged [bitwise]

For challenges involving doing something on the bit level.

57 questions
Filter by
Sorted by
Tagged with
299 views

### Interpreting the Wolfram Code

Introduction An elementary cellular automaton is a cellular automaton that is 1-dimensional and has 2 states, 1 and 0. These cellular automata are categorized based on a simple code: the Wolfram code,...
255 views

### Mirror, Mirror, on the wall. Who's the fairest of them all?

Well, you know it's Snow White, and the evil Queen is at it again. Will Snow White be saved? Will she fall asleep once again? Will the Prince find her? Challenge: Given an arbitrary number (>= 2) of ...
5k views

### Floating Point XOR

Your task is pretty simple. Given two floats, bitwise xor the binary representation of them, and output that as a float. For example, ...
2k views

### Decode a variable-length quantity

A variable-length quantity (also referred to as VLQ or uintvar) is a way to encode up to a 28 bit integer value using only as many bytes as necessary. This was used ...
1k views

### String to Bit Transition

Task Given an input string of one or more ASCII characters which codepoints are between 0 and 128 (exclusive), do the following: Convert each character into its 7-bit ASCII code (if the ASCII code ...
1k views

### Can a neural network recognize primes?

Background Recognizing primality seems like a poor fit for (artificial) neural networks. However, the universal approximation theorem states that neural networks can approximate any continuous ...
2k views

### Compare four integers, return word based on maximum

This function should take four integer inputs (a,b,c,d) ...
228 views

### (bit)Wise Images [closed]

Given a truth table and two images, use the truth table as a bitwise operation to the two images. For example with the truth table: 1 0 1 0 0 0 1 0 (Note that ...
5k views

### Find the number of leading zeroes in a 64-bit integer

Problem: Find the number of leading zeroes in a 64-bit signed integer Rules: The input cannot be treated as string; it can be anything where math and bitwise operations drive the algorithm The ...
2k views

### Toggle some bits and get a square

Given an integer $N>3$, you have to find the minimum number of bits that need to be inverted in $N$ to turn it into a square number. You are only allowed to invert bits below the most ...
3k views

### Double, XOR and do it again

We define the function g as g(n) = n XOR (n * 2) for any integer n > 0. Given x > 0, find the smallest integer y > 0 such that gk(y) = x for some k > 0. Example ...
326 views

### Wanna be an Alchemist

Wanna be an Alchemist I've been watching Full Metal Alchemist these past days and I've been wondering, It is really possible to trans-mutate matter? In the real world, I don't know if it is possible, ...
2k views

### XOR sort an array

Given a key, and an array of strings, shuffle the array so that it is sorted when each element is XOR'd with the key. XOR'ing two strings To XOR a string by a key, XOR each of the character values ...
1k views

### Alternating bit smearing

Introduction This challenge requires you to set the trailing zeros of an integers binary representation to 010101…, this is best explained with an example: Given ...
576 views

### Bitwise XOR of rational numbers

Introduction Every rational number between 0 and 1 can be represented as an eventually periodic sequence of bits. For example, the binary representation of 11/40 is ...
4k views

### Calculate the longest series of 1's in an integer's binary value

Goal Given a non-negative integer, create a function that returns the starting position of number of largest consecutive 1's in that integer's binary value. When given an input ...
248 views

### Find the Closest Double Palindrome

Given a double-precision float, find the closest double-precision float whose binary representation is a palindrome. Input A floating point number x. You may use ...
2k views

### Exploring the xorspace

The xorspace of a set of integers is the set of all integers that can be obtained by combining the starting integers with the usual bitwise xor operator (^). For ...
2k views

### Do two numbers contain unique powers of 2

Break two numbers up into their powers of 2, if they share any, return a falsey value. Otherwise, return a truthy value. If one input is 0, the answer will always ...
2k views

### Different number, same weight

Background The Hamming weight of an integer is the number of ones in its binary representation. For this challenge, integers are represented with 32 bits, and they are unsigned. Challenge Given an ...
597 views

### Make Wise Numbers

Wise is a simple bitwise language I designed a while back. It is based around Python's bitwise operations. It has several operations most of these are the same or very similar to the equivalent ...
2k views

### Digital Hardness of Integers

To find the digital hardness of an integer, take its binary representation, and count the number of times both a leading and trailing 1 can be removed until it ...
766 views

### Binary Convolution

A binary convolution is described by a number M, and is applied to a number N. For each bit in the binary representation of <...
878 views

### Super Folding Numbers

We have already defined a folding number here. But now we are going to define a Super Folding Number. A Super Folding number is a number that if folded enough times it will eventually reach one less ...
3k views

### Folding Numbers

Given a number determine if it is a folding number. A folding number is a number such that if you take it binary representation and "fold" it in half, That is take the result of XNOR multiplication ...
3k views

### Bitflip and negate

Given an integer, make an expression that produces it from 0 using unary negation - and bitwise complement ...
3k views

### Golf bit weaving

Note: the first half of this challenge comes from Martin Ender's previous challenge, Visualize Bit Weaving. The esoteric programming language evil has an interesting operation on byte values which it ...
3k views

### 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-...
2k views

### “Bit-borrow” two numbers

Did you know that a small number can borrow bits from a larger number? Here's an example. Let's say our two numbers 5 and 14. First, write them out in binary: ...
3k views

### 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 each ...
1k views

### Compute CRC32 Hash

Credits This challenge originated from @miles. Create a function that computes the CRC32 hash of an input string. The input will be an ASCII string of any length. The output will be the CRC32 hash ...
4k views

### Generate a parity bit

A parity bit, is one of the simplest forms of a checksum. First, you have to pick the parity, even or odd. Let's say we pick even. Now, we need a message to transmit. Let's say our message is "Foo". ...
5k views

### Split a byte array into a bit array

Write a function that when given a buffer b (1 - 104857600 bytes long) and a number of bits n (1 <= n <= 64), splits the ...
2k views

### The XOROR sequence

Cellular Automata are truly fascinating. The ones that are usually talked about are the binary ones, i.e., the ones representable by a number. However, those, in my opinion, have been done to death. ...
248 views

Introduction There are often times that we have challenges which require communication of some sort (such as in team KOTH), where density of information may be more important than density of code. ...
523 views

### Bijective mapping from integers to a variable number of bits

A variable number of bits is an array of 0 or more bits. So [0, 1] is a variable number of bits, but so is []. Write a function ...
11k views

### Cheating a multiple choice test

Introduction While studying, I tried to come up with several ways to cheat a multiple choice test. It basically is a compressed version of the multiple choice answers. The method goes as following: ...
5k views

### Xorting an array

Conceptually, this challenge is really simple. You're given a list of non-negative integers ai. If possible, find a non-negative integer ...
2k views

### Produce an XOR table

Introduction XOR is a digital logic gate that implements an exclusive or. Most of the times, this is shown as ^. The four possible outcomes in binary: ...
490 views

Background Inspired by this Unix.SE question (and of course my own answer). When an IP address is specified for an interface, it is often given in this dotted-decimal form: ...
2k views

### 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 ...
1k views

### Find the XOR Primes

In this challenge posed by xnor, we were asked to implement XOR multiplication. In this challenge the goal is to find the first n XOR primes. XOR primes are very ...
63 views

### Check if a given 8-bit Number is sparse [duplicate]

The task is the following: Program the shortest fully functional program that checks, if an 8-bit value contains a consecutive sequence of 2 or more ones in its binary form. If it does contain such ...
5k views

### Programming with Bits and Bytes

In this challenge you are going to write an interpreter for a simple language I've made up. The language is based on a single accumulator A, which is exactly one byte in length. At the start of a ...
919 views

### Summation under Zeckendorf Representation

Zeckendorf's theorem shows that every positive integer can be uniquely represented as a sum of non-adjacent Fibonacci numbers. In this challenge, you have to compute the sum of two numbers in ...
7k views

### XOR multiplication

You goal is to implement the operation of XOR (carryless) multiplication, defined below, in as few bytes as possible. If we think of bitwise XOR (^) as binary ...
864 views

### Shifty XORyption

Write a program or function (or set of programs/functions) to encrypt and decrypt data given the following specification: Encryption Calculate an XOR hash of the input by XOR-ing every byte with ...
669 views

### Unwise bit operations

I like to golf in dc, but I'm sometimes frustrated because dc doesn't have bitwise operations. Challenge Provide four named ...