476. Number Complement -E

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/

A:

就是简单的位运算

class Solution {
public:
    int findComplement(int num) {
        int res = 0;
        for(int i =0;i<32 and num>0;++i)
        {
            int tmp = num & (1<<i);
            if(tmp==0){
                res += 1<<i;
            }else{
                num -= tmp;
            }
        }
        return res;
    }
};