LintCode刷题笔记-- A+B problem

位运算

描述

Write a function that add two numbers A and B. You should not use + or any arithmetic operators.

解题思路：

利用位运算来解决A+B的问题，可以将此问题转化为解决不进位相加和进位(carry bit)的两部分问题：

1. 首先是不进位相加：_A = A^B 先对A和B进行异或运算(XOR manupitation) , A 和B 中两位不相同的变为1，相同的变为 0， 同为1是不进位

2. 其次是进位  _B =(A&B)<<1

所以 A+B = A^B + (A&B)<<1

3.在循环中(A&B)<<1 的目的是将要进位的1一直向左移动，之后与新生成的_A进行异或运算，来进行进位运算的模拟（这一步就是进位）

4. 直到将所有的1全部向左移位为0

参考代码：

时间： 2024-11-29 13:50:28

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