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.

Credits:
Special thanks to @fujiaozhu for adding this problem and creating all test cases.

在位操作中，a ^ b能得到进位，a & b能得到相加后还没加进位的数，上面两步一直循环，直到carry等于0，就能得到最后的结果。代码如下：

public class Solution {    public int getSum(int a, int b) {        if (a == 0) {            return b;        }        if (b == 0) {            return a;        }        while (b != 0) {            int carry = a & b;            a = a ^ b;            b = carry << 1;        }        return a;    }}