LeetCode-342. Power of Four

class Solution {
public:
bool isPowerOfFour(int num) {
int num1 = num - 1;
if((num&num1)==0){                //insure num is the power of 2
if((num&0x55555555)!=0){	  //insure num has even number zero
return true;
}
}
return false;
}
};