# 67. Add Binary
"""
given two binary strings 'a' and 'b', return their sum as a binary string.
"""
class Solution(object):
def addBinary(self, a, b):
"""
:type a: str
:type b: str
:rtype: str
"""
ans, carry = [], 0
i, j = len(a) - 1, len(b) - 1
while i >= 0 or j >= 0 or carry:
if i >= 0:
carry += int(a[i])
i -= 1
if j >= 0:
carry += int(b[j])
j -= 1
ans.append(str(carry % 2))
carry //= 2
return "".join(reversed(ans))
if __name__ == "__main__":
obj = Solution()
print(obj.addBinary(a="11", b="1"))
print(obj.addBinary(a="1010", b="1011"))
