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.

不用+和-运算符，求a和b的和。用为运算的方法。根据a+b = a^b + (a&b)<<1，用递归的方法求和即可。

代码：

class Solution {
public:
    int getSum(int a, int b) 
    {
    	int tmp=a;
        a=a^b;
        b=(tmp&b)<<1;
        while(b)
        {
        	tmp=a;
        	a=a^b;
        	b=(tmp&b)<<1;
        }
        return a;
    }
};