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

For example,
a = "11"
b = "1"

Return "100".


class Solution(object):
    def addBinary(self, a, b):
        """
        :type a: str
        :type b: str
        :rtype: str
        """
        a_int = int(a,2)
        b_int = int(b,2)
        return bin(a_int+b_int)[2:]