Every non-negative integer N has a binary representation.  For example, 5 can be represented as "101" in binary, 11 as "1011" in binary, and so on.  Note that except for N = 0, there are no leading zeroes in any binary representation.
The complement of a binary representation is the number in binary you get when changing every 1 to a 0 and 0 to a 1.  For example, the complement of "101" in binary is "010" in binary.
For a given number N in base-10, return the complement of it's binary representation as a base-10 integer.
Example 1:
Input: 5
Output: 2
Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.
Example 2:
Input: 7
Output: 0
Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.
Example 3:
Input: 10
Output: 5
Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.
Note:
0 <= N < 10^9
This question is the same as 476: https://leetcode.com/problems/number-complement/
class Solution:
    def bitwiseComplement(self, N: int) -> int:
        
        if N==0:
            return 1
        
        dummy_num=N
        
        n=0
        while(dummy_num):
            n+=1
            dummy_num>>=1
        
        ans=0
        
        for i in range(n-1,-1,-1):
            
            if (N>>i)&1==0:
                ans|=(1<<i)
                
            
        return ans
class Solution:
    def bitwiseComplement(self, N: int) -> int:
        
        if N==0:
            return 1
        
        dummy_num=N
        
        n=0
        while(dummy_num):
            n+=1
            dummy_num>>=1
        
        ans=0
        
        for i in range(n-1,-1,-1):
            
            if (N>>i)&1==0:
                ans|=(1<<i)
                
            
        return ans