https://leetcode.com/problems/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.

注释，这个题目有意思，学过FPGA的人都知道最基本的半加器和全加器是最基本的东西，这里也是这样计算加法的。

int getSum(int a, int b) {if(b == 0)return a;int sum = a^ b;int cout = (a & b) << 1;return getSum(sum, cout);
}