[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;//忽略進位，先將各位相加
            int y = (a & b) << 1;//計算出進位，並將進位左移一位，以便後續相加
            a = x; b = y;//將進位左移的結果和忽略進位的和相加
        }
        return a;
    }
};