LeetCode: 476 Number Complement(easy)

题目：

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

　　　Note:

1. 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.

代码：

class Solution {
public:
    int findComplement(int num) {
        int x = 0, p = 0;
        while(num){
            if(num%2==0) x |= (1 << p);
            ++p;
            num/=2;
        }
        return x;
    }
};