0190-reverse-bits.js

/**
 * https://leetcode.com/problems/reverse-bits/
 * Time O(1) | Space O(1)
 * @param {number} n - a positive integer
 * @return {number} - a positive integer
 */
var reverseBits = function (n, bit = 0) {
    for (let i = 0; i < 32; i++) {
        bit <<= 1;      // Double * 2
        bit |= (n & 1); // Flip
        n >>=  1;           // Reduce * 0.5
    }

    return bit >>> 0;
};