Leetcode476. Number Complement

class Solution {
public:
    int findComplement(int num) {
        int ans=0;
        for(int i=0;num!=0;i++){
            int x=num%2;
            if(x==0){
                ans+=(int)(pow(2.0,i)+0.5);
            }
            num/=2;
        }
    return ans;
    }
};