Number Complement

Description

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

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.

3. This question is the same as 1009: https://leetcode.com/problems/complement-of-base-10-integer/

code:

class Solution {
    public int findComplement(int num) {
        int res = 0;
        int base = 1;
        while (num != 0) {
            int bit = (num & 1) == 1 ? 0 : 1;
            res += bit * base;
            num >>= 1;
            base *= 2;
        }
        return res;
    }
}