0371-sum-of-two-integers.adoc

371. Sum of Two Integers

{leetcode}/problems/sum-of-two-integers/[LeetCode - Sum of Two Integers^]

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

思路分析

n = a ⊕ b 非进位和：异或运算

c = a & b << 1 进位：与运算+左移一位

这道题的关键有几点：

1. 通过异或操作获取在不进位的情况下，各位的值；

2. 通过相与加移位来来获取各个进位项；

3. 重复上面的操作，直到进位项为 0 为止。

思考题：思考如何通过位运算来实现加减乘除？

一刷

link:{sourcedir}/_0371_SumOfTwoIntegers.java[role=include]

二刷

link:{sourcedir}/_0371_SumOfTwoIntegers_2.java[role=include]

参考资料

1. {leetcode}/problems/sum-of-two-integers/discuss/84278/A-summary%3A-how-to-use-bit-manipulation-to-solve-problems-easily-and-efficiently[A summary: how to use bit manipulation to solve problems easily and efficiently - LeetCode Discuss^]