python不用加号实现加法

问题:

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.

Example:
Given a = 1 and b = 2, return 3.

class Solution(object): def getSum(self, a, b): """         :type a: int :type b: int :rtype: int
        """         if(0 == b): return a sum1 = a^b carry = (a&b)<<1
        return Solution().getSum(sum1,carry) if __name__ == '__main__'： l = Solution().getSum(3,7) print l