[LeetCode]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.

class Solution {
public:
    int getSum(int a, int b) {
         while (b){
            int x = a ^ b;//忽略进位，先将各位相加
            int y = (a & b) << 1;//计算出进位，并将进位左移一位，以便后续相加
            a = x; b = y;//将进位左移的结果和忽略进位的和相加
        }
        return a;
    }
};