Count Number of Bits to be Flipped to Convert A to B using JavaScript

Given two numbers, A and B. Write a program to count the number of bits needed to be flipped to obtain B from A. 

Examples: 

Input: A = 10, B = 20
Output: 4
Explanation: Binary representation of A is 00001010
Binary representation of B is 00010100
We need to flip highlighted four bits in A to obtain B from it.

Input: A = 7, B = 10
Output: 3
Explanation: Binary representation of A is 00000111
Binary representation of B is 00001010
We need to flip highlighted three bits in A to obtain B from it.

Below are the approaches to Count Number of Bits to be Flipped to Convert A to B using JavaScript:

Using the XOR operator

We can use the XOR operator (^) to find the bits that are different between A and B. Then, we count the number of set bits (bits with value 1) in the result.

Example: Implementation of a program to find the Number of bits to be flipped to obtain B from A using the XOR operator

Using XOR Operator: 4

Time Complexity: O(log(max(A, B)))

Auxiliary Space: O(1)

Using the AND operator

We first Iterate through each bit of numbers A and B and than use AND operator to extract the least significant bit of A and B.If the bits are different, increment the flips count, and then right shift A and B to check the next bit.

Example: Implementation of program to find Number of bits to flipped to obtain B from A using the AND operator

Using AND Operator: 4

Time Complexity: O(log(max(A, B)))

Auxiliary Space: O(1)