LeetCode——Sum of Two Integers

LeetCode——Sum of Two Integers

Question

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.

Solution

异或操作有累加的效果，但是没有进位的效果。什么时候进位呢？ 同时为1的时候进位，往前进一位，所以用交集操作，再移位，表示进位。

Answer

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