476. Number Complement

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.

code

func findComplement(_ num: Int) -> Int {
    var temp = num, mask = 1;
    while(temp != 0) {
        temp = temp >> 1;
        mask = mask << 1;
    }
    temp
    mask
    return num ^ (mask - 1);
    
}