NumberComplement.js

// Source : https://leetcode.com/problems/number-complement
// Author : Dean Shi
// Date   : 2017-07-10

/***************************************************************************************
 *
 * Given a positive integer, output its complement number. The complement strategy is
 * to flip the bits of its binary representation.
 *
 * Note:
 *
 * The given integer is guaranteed to fit within the range of a 32-bit signed integer.
 * You could assume no leading zero bit in the integer’s binary representation.
 *
 * Example 1:
 *
 * Input: 5
 * Output: 2
 * Explanation: The binary representation of 5 is 101 (no leading zero bits), and its
 * complement is 010. So you need to output 2.
 *
 * Example 2:
 *
 * Input: 1
 * Output: 0
 * Explanation: The binary representation of 1 is 1 (no leading zero bits), and its
 * complement is 0. So you need to output 0.
 *
 *
 ***************************************************************************************/

/**
 * @param {number} num
 * @return {number}
 */
var findComplement = function(num) {
    const i = 1 << num.toString(2).length
    return (i - 1) ^ num
};