题目：

题解：

class Solution {
public:
    int findComplement(int num) {
        int pos;
        for (int i = 30; i >= 0; i--) {
            if (num & (1 << i)) {
                pos = i;
                break;
            }
        }
        return (((1LL << (pos + 1)) - 1) ^ (num));
    }
};