Number Complement问题及解法

发布于:2021-08-02 19:57:53

问题描述:



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.
示例:


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.

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.


问题分析:


将一个正整数的二进制表示按位取反,得到答案,以上两者二进制均没有前导零。




过程详见代码:



class Solution {
public:
int findComplement(int num) {
unsigned mask = ~0;
while (num & mask) mask <<= 1;
return ~mask & ~num;
}
};





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