# Questions tagged [bit-manipulation]

The tag has no usage guidance.

78 questions
Filter by
Sorted by
Tagged with
78 views

166 views

### How are bitwise operators used in normalisation of floating-point numbers?

After having spent a significant amount of time googling this topic, I am still struggling to confidently answer the following question: ...
30 views

### Number of subsequence's with same values of bitwise and, or and xor

GeeksForGeeks We are given an array arr of $n$ element. We need to count number of non-empty subsequences such that these individual subsequences have same values of bitwise AND, OR and XOR. For ...
210 views

### Given matrix, count paths visiting each number exactly once

We are given matrix of size at most $21$ by $21$, each number of the matrix is either $-1$, which means empty element, or integer between $1$ and $21$. Each integer may occure several more times in ...
45 views

### What is the reason for this contradiction about the size of the char type?

the size of one char in C is 4 bytes, however to define an 'A' character we use the sum of two values like this expression here: or in other way i want to say that the char is 4 bytes size, but in ...
52 views

### Why is the time complexity of the Bit Manipulation solution to Binary Addition O(M + N)?

I am trying to understand why the time complexity of the Bit Manipulation solution (https://leetcode.com/problems/add-binary/solution/) to the Binary Addition problem is O(M + N), where M and N are ...
122 views

### Complexity of n & (n - 1) should be O(1) or O(log n)?

I'm looking at the methods posted in https://www.geeksforgeeks.org/program-to-find-whether-a-no-is-power-of-two/ for checking whether n is a power of 2. Method 5, ...
67 views

### Shuffling Bits For Uniform Distribution

I am writing a hashing algorithm to be used in the key-value data store. That is for each key the location of the data is determined. The structure of the data store is given a key, a value needs to ...
34 views

### A small question about generating random variable with geometric distribution

I was reading Professor Knuth's Volume 2 (page 136) about generating a geometrically distributed random variable $N$ (with $p$ as the probability of success). Basically, the idea is to generate a ...
51 views

### Maximize AND on a sequence of XORs

Problem We are given 2 arrays a and b both of length n. We build a third array ...
2k views

### How to find the largest power of two divisor of a given integer?

Given an integer $x$, I need to find the largest power of two $p = 2^n$ that divides $x$ such that the remainder is zero. When $x$ is zero, the algorithm should return zero. For odd numbers, it should ...
110 views

### Dividing 2 integers with some constraints

This a problem i came across while practicing binary search. Here is the problem: Given two integers dividend and divisor, divide two integers without using multiplication, division and mod operator. ...
127 views

### while loop for bitwise conversion program

int counter(char c){ int count = 0; while (c!=0){ if((c & 1) !=0) count++; c = c >> 1; } } I am trying to understand a ...
21 views

### What is the order of magnitude of bitwise operations involved in a SHA-256 hash?

Specifically, how many bitwise operations (approximately, could be just order of magnitude) occur each time a Bitcoin ASIC miner performs a SHA-256 hash in typical mining computation, i.e. as it ...
65 views

### Compressing a bit string when I know how many 1s and 0s there are

Say I have a 256 bit bit-string, and I know that there are 16 ones and 240 zeros. I know that this bit string can be compressed, because there are only 256 choose 16...
220 views

### Must a Turing machine tape be binary?

I once asked why does computer data bits are usually organized on binary (base 2) sets, rather than on unary (base 1) sets, aiming to also understand why its not also ternary (base 3), heptary (base 7)...
44 views

### Book CS:APP, using bit set and bit clear

Okay so I'm going through a book CS:APP. I'm in chapter 2. And problem 2.13 talks about how the Digital Equipment VAX computer used bis (bit set) and bic (bit clear) instead of Boolean operations AND ...
64 views

### How can I prove or disprove that the following function is bijection?

For a research project, I tried to prove or disprove that a function called xxhash128_low is a bijection from 64 bit unsigned integer to 64 bit unsigned integer. I have shown that it is sufficient to ...
2k views

### ip/tcp packet decoding without wireshark

How can we manually read and interpret packets properly without using wireshark? Now from the Ethernet header I know that the Destination MAC Address should be at the 5th byte (after converting bits/...
33 views

146 views

### Minimum number of ways to write a string

Consider the following question There are K magical pens (numbered 1 through K). You are given strings P1,P2,…,PK (each of which consists of characters from 'a', 'b', …, 't') ; for each valid i, the ...
1k views

168 views

### How to solve Assigment problem on SPOJ? [closed]

Problem Link - Assign .This problem is known as assignment problem. I read few solutions Here is one and they are trying to solve it using Bit-masking and DP .I tried and thought hard to ...
104 views

### find maximum sum of xors

we are given an Array Array size <= 10^4 . 0 <= A[i] <= 15 We need to partition the array into 4 subsets (each subset can have zero or more elements ). Take xor of each subset and sum ...