476. Number Complement

Link: https://leetcode.com/problems/number-complement/

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation.

Note:

1. The given integer is guaranteed to fit within the range of a 32-bit signed integer.
2. 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.

class Solution(object):
    def findComplement(self, num):
        """
        :type num: int
        :rtype: int
        """
        if not num:
            return 1

        result = 0
        exponent = 0
        while num != 0:
            if num & 1 == 0:
                result += 1 * (2 ** exponent)

            num >>= 1
            exponent += 1

        return result