Sum of Two Integers

update Jan 26,2018 22:09

LeetCode

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.

Basic Idea:

每次用 a & b << 1 计算出进位，用 a ^ b 算出每一位相加后 mod 2 的值，再把这两个值相加，直到进位为 0；

• Java Code:

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