1009-complement-of-base-10-integer.cpp

class Solution {
public:
    int bitwiseComplement(int n) {
        
        int m = n;
        int mask = 0; 
        // Edge Case (Exception)
        if(n == 0) return 1;
        
        while(m != 0){
            mask = (mask << 1) | 1;
            m = m >> 1;
        }
        int ans = (~n) & mask;
        return ans;
    }
};