Questions tagged [bitwise]
For challenges involving bitwise commands or manipulation of numbers at the bit level
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XOR of independent Bernoulli variables
In probability theory, a Bernoulli variable is a random variable which has a single parameter \$p\$, and is equal to 1 with probability \$p\$, and 0 with probability \$1-p\$.
In this challenge, there ...
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making a binary string palindrome using xor operations [closed]
Problem
You are given a binary string A of length N.
You can perform the following type of operation on the string A:
Choose two different indices \$i\$ and \$j\$ (\$1 \le i\$, \$j \le N\$)
Change \$...
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Count the number of disjoint 11 blocks
The task is to count the number of disjoint 11 blocks in a 64-bit word, using the minimum number of straight-line instructions. That is, how many nonoverlapping ...
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3
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Shift distance of number [closed]
Given two non-zero 16-bit integers a and b, decide the smallest number of shift operations needed to turn ...
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3
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360
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Smallest and largest 100-bit square with maximum Hamming weight
Introduction
In the binary representation of a \$k-\$bit \$(k>1)\$ square number \$n^2, \$ not all bits can be \$1\$. The maximum number of \$1\$-bits (Hamming weight, \$B\$ for short) is given in ...
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Inverting string-based binary number in one line in Python
I want to read two strings on separate lines, each string the same length and containing only 0's and 1's, and determine if the first is the one's complement of the second. How succinctly can this be ...
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Double bit rotation to the right [closed]
Given a positive integer as input, output that integer, but with its bits rotated two times to the right. Also, think of the number as a donut of bits, eg. ...
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4
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Calculate the truncated log2 of some unsigned integer [duplicate]
Definition
Given some number, x calculate the smallest number i such that 2i≥x. This is not a duplicate of this question. It is slightly different in that an input of 16 should yield an output of 4 ...
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Dr. Lamport's Unfinished Business
Introduction
Dr. Leslie Lamport, of the eponymous Lamport one-time signature scheme, is getting rather old. But he can't die until his most famous algorithm gets all the kinks ironed out!
In ...
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answers
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Golf this Thumb-2 Constant!
One thing that is constantly frustrating when golfing ARM Thumb-2 code is generating constants.
Since Thumb only has 16-bit and 32-bit instructions, it is impossible to encode every immediate 32-bit ...
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Find the "Bittiest" Number [closed]
The Challenge
Given a list of integers, the "bittiest" number among them is the one with the most bits on - that is, the largest amount of bits set to 1.
Write a function (or a program) that ...
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The Koszul Sign Rule
A Bit of Background
The exterior algebra is a central object in topology and physics (for the physics concept cf. fermion). The basic rule dictating the behavior of the exterior algebra is that \$yx =...
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Simulate D Flip-Flop
Objective
Simulate an edge-triggered D Flip-Flop.
What is D Flip-Flop?
A D flip-flop is an electronic digital device that outputs an inputted data (abbr. D) with synchronization to a clock (abbr. ...
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Summing a sub-square of a quarter of an infinite chessboard
Description of the problem
Imagine a quarter of an infinite chessboard, as in a square grid, extending up and right, so that you can see the lower left corner. Place a 0 in there. Now for every other ...
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Computational Parity Party! [duplicate]
The computational parity of an integer is defined as 1 if the integer has an odd number of set bits, and 0 otherwise. (src).
Input
You will receive one nonnegative integer that you will take the ...
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votes
12
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Compress 8 bits to 6 when certain bit patterns will never occur
Consider an eight bit number in which an even position bit will never be 1 if one of its neighbors is 0 (considering MSB and LSB as neighbors). There are fewer than 64 such numbers, so there is at ...
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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,...
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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) ...
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votes
22
answers
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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,
...
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votes
22
answers
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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 ...
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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 is ...
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votes
2
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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 ...
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answers
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Compare four integers, return word based on maximum
This function should take four integer inputs (a,b,c,d) ...
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(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 ...
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votes
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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 ...
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votes
17
answers
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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 ...
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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
...
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votes
2
answers
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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, ...
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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 ...
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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 ...
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23
votes
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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
...
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votes
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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 ...
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votes
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answer
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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 ...
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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 ...
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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 ...
- 10.2k
22
votes
19
answers
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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 ...
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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 ...
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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 ...
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answers
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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 <...
user45941
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votes
9
answers
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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 ...
- 95.5k
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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 ...
- 95.5k
42
votes
29
answers
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Bitflip and negate
Given an integer, make an expression that produces it from 0 using unary negation - and bitwise complement ...
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votes
22
answers
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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 ...
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votes
30
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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 \$2^n\$ ...
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"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:
...
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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 each ...
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answers
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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 of ...
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votes
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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 "...
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votes
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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 ...
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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. ...
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