[LeetCode&Python] Problem 371. Sum of Two Integers

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

Example 1:

Input: a = 1, b = 2
Output: 3

Example 2:

Input: a = -2, b = 3
Output: 1

 

class Solution(object):
    def getSum(self, a, b):
        """
        :type a: int
        :type b: int
        :rtype: int
        """
        MAX = 0x7FFFFFFF
        #符号位为0的最大值
        Mask = 0xFFFFFFFF
        #符号位为1的最大值
 
        while b!=0:
            suma=(a^b)&Mask
            carry=((a&b)<<1)&Mask
            a=suma
            b=carry
 
        return a if a<=MAX else ~(a^Mask)
 
#Python 比较麻烦的地方是 要Mask.....