# Time: O(n) # Space: O(1) # # Given two binary strings, return their sum (also a binary string). # # For example, # a = "11" # b = "1" # Return "100". # class Solution: # @param a, a string # @param b, a string # @return a string def addBinary(self, a, b): result, carry, val = "", 0, 0 for i in xrange(max(len(a), len(b))): val = carry if i < len(a): val += int(a[-(i + 1)]) if i < len(b): val += int(b[-(i + 1)]) carry, val = val / 2, val % 2 result += str(val) if carry: result += str(carry) return result[::-1] if __name__ == '__main__': result = Solution().addBinary('11', '1') print result