Add Binary (in Python)

Problem

Given two binary strings, return their sum (also a binary string).

The input strings are both non-empty and contains only characters 1 or 0.

Example 1:

Input: a = "11", b = "1"
Output: "100"

Example 2:

Input: a = "1010", b = "1011"
Output: "10101"

Solution

class Solution:
    def addBinary(self, a, b):
        """
        :type a: str
        :type b: str
        :rtype: str
        """
 
        # ans = int(a, 2) + int(b, 2)
        # return "{0:b}".format(ans)
 
        a_int = int(a, 2)
        b_int = int(b, 2)
        
        carry = 1
        
        while carry:
            # 1&1=1. carry 쉽게 계산 가능.
            carry = (a_int & b_int) << 1
            #1^1=0^0=0, 1^0=0^1=1
            a_int = a_int ^ b_int
            b_int = carry
            
        return "{0:b}".format(a_int)

Source 

https://leetcode.com/problems/add-binary/