461. Hamming Distance

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.

 

 

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class Solution {
public:
    int findComplement(int num) {
        int n = 0;
        int tmp = num;
        while(tmp>0){
            tmp>>=1;
            n++;
        }
        return ((1<<n)-1)&(~num);
    }
};