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

Solution：

思路：
https://leetcode.com/problems/sum-of-two-integers/discuss/84290
Time Complexity: O(N) Space Complexity: O(N)

Solution Code：