Add Binary

Question

https://leetcode.com/problems/add-binary/?tab=Description

Analysis

Utilize the recursion.

Code

class Solution(object):
    def addBinary(self, a, b):
        """
        :type a: str
        :type b: str
        :rtype: str
        """
        if a == '':
            return b
        elif b == '':
            return a
        elif a[-1] == '1' and b[-1] == '1':
            return self.addBinary(self.addBinary('1', a[:-1]), b[:-1]) + '0'
        elif a[-1] == '0' and b[-1] == '0':
            return self.addBinary(a[:-1], b[:-1]) + '0'
        else:
            return self.addBinary(a[:-1], b[:-1]) + '1'