BIT operations:

 

BIT operations:

Terminology:

Bit is set: bit value is 1 at that position.

  1. The & (bitwise AND) takes two numbers as operands and does AND on every bit of two numbers. The result of AND is 1 only if both bits are 1.  
  1. The | (bitwise OR) takes two numbers as operands and does OR on every bit of two numbers. The result of OR is 1 if any of the two bits is 1. 
  1. The ^ (bitwise XOR) takes two numbers as operands and does XOR on every bit of two numbers. The result of XOR is 1 if the two bits are different. 
  1. The << (left shift) takes two numbers, the left shifts the bits of the first operand, and the second operand decides the number of places to shift. Can be used to multiply by 2 power (n) example a<<b means a* 2Power (b).  also a&(1<<n)  will tell whether nth bit is set on a or not.
  1. The >> (right shift) takes two numbers, right shifts the bits of the first operand, and the second operand decides the number of places to shift. Can be used to divide by 2 power (n) example a<<b means a/ 2Power (b). (num>>i)&1 can tell you ith bit from right is set or not, returns 1 if set and 0 if not set, you can do it for n numbers to count how many numbers have ith bit set.
  1. The ~ (bitwise NOT) takes one number and inverts all bits of it.

 

Note: If we perform operations on two ints then it will perform operation on each bits of two numbers and result the output by forming the number using resulting bit sequence after the operation.

Comments

Post a Comment

Popular posts from this blog

LeetCode 3Sum

Question Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that i != j, i != k, and j != k, and nums[i] + nums[j] + nums[k] == 0. Notice that the solution set must not contain duplicate triplets. Brute force We can run 3 loops to check each possible triplets, we also need to eliminate the duplicates from both sides. this method will work but will work but will give time limit exceed after time constraints. To do this in given time limit we need to sort the array first and Create a loop that fixes the left most integer. This reduces the problem to 2sum for remaining array. For each loop iteration where duplicates are skipped, we need to do a left/right iteration using while loop. my code:
Read more

New start Day 2 (1/10/2020) codeforces 492B Vanya and Lantern

 question: (source: https://codeforces.com/problemset/problem/492/B)      Vanya And Lantern Vanya walks late at night along a straight street of length  l , lit by  n  lanterns. Consider the coordinate system with the beginning of the street corresponding to point  0 , and its end corresponding to the point  l . Then the  i -th lantern is at the point  a i . The lantern lights all points of the street that are at the distance of at most  d  from it, where  d  is some positive number, common for all lanterns. Vanya wonders: what is the minimum light radius  d  should the lanterns have to light the whole street? Input The first line contains two integers  n ,  l  ( 1 ≤  n  ≤ 1000 ,  1 ≤  l  ≤ 10 9 ) — the number of lanterns and the length of the street respectively. The next line contains  n  integers  a i  ( 0 ≤  a i  ≤  l ). Multiple lanterns can be loca...
Read more

Heap (min)

 Heap Heap is a data structure used to store numbers in form of binary tree i.e each node has two children. Heap is the data structure behind PriorityQueue. Insert and pop operation inside a heap is oh log(n) complexity and can be used in multiple insert and pop operation questions. It is efficient and used in fastest sorting as well as sorting only takes nlog(n) complexity at worst case. Important Functions for heap: 1.  Heapify: This function is a top down approach to set an given array into heap. The idea is to set the top priority Item at the parent node of given subtree of 3. We will compare priority of left item from parent and then from right item to that of winner of parent and left and then swap the top priority with parent item. If top priority wasn't the parent item then we call the heapify again for the right or left node with which the value was swapped. If we have a given array then we can run a loop into that array from bottom of tree to top (excluding leafs),i....
Read more