Bitwise AND of Numbers Range

Leetcode Problem 201: Bitwise AND of Numbers Range

Problem Summary

Given two integers left and right representing an inclusive range [left, right], return the bitwise AND of all integers in that range.

Constraints:

• Both left and right are non-negative integers up to 2,147,483,647 (2^31 − 1).
• left <= right.

Techniques

• Bit Manipulation

Solution

function rangeBitwiseAnd(left: number, right: number): number {
    let shift = 0

    while (left !== right) {
        left = left >> 1
        right = right >> 1
        shift++
    }

    return left << shift
};

// Beautiful solution from ChatGPT notes => use xor to find the different bits and then use the mask to get the result (common bits between left and right)
function rangeBitwiseAnd2(left: number, right: number): number {
    let diff = left ^ right;  
    let mask = ~diff + 1;     
    return left & mask;
};

console.log(rangeBitwiseAnd(5, 7))