371.Sum of Two Integers

Tags: Easy Bit Manipulation

Links: https://leetcode.com/problems/sum-of-two-integers/

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Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.

Example 1:

Input: a = 1, b = 2
Output: 3

Example 2:

Input: a = -2, b = 3
Output: 1

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

        return a;
    }
};

异或运算的特点是不进位加法，如果两数字对应位上是1则进位，所以用与运算解决，最后结果相加，继续递归调用，当没有进位时停止。

注意的是程序第6行，如果是int类型，输入是1和-1时候会溢出。