leetcode week4

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.

问题描述：给定一个正整数，输出为它的补，这里的补即二进制表示的每一位都取反。

解题思路：对于给定的正整数的二进制表示，我们要知道长度，然后用对应长度且全为1的二进制串取异或。因为这里无法知道具体的长度，所以可以一位一位取异或。

class Solution {public:    int findComplement(int num) {        long i;        for(i=1;i<=num;i*=2){            num^=i;        }          return num;    }};