leetcode 476. Number Complement

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本文介绍了一种求正整数补数的算法实现。通过翻转输入整数的二进制表示中的每一位比特位，得到其补数。文章提供了一个具体的C++实现案例，并通过两个例子说明了该算法的工作原理。

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.

一位一位来，如果约0，那就变成1。需要加上。

class Solution {
public:
    int findComplement(int num) 
    {
        if (num == 0) return 1;
        int k = 1, ret = 0;
        while (num)
        {
            if (num % 2 == 0)    
            {
                ret += k;
            }
            k *= 2;
            num /= 2;
        }
        return ret;    
    }
};