leetcode 371. 两整数之和机组二进制加法

清疚 2022-04-24 08:28 168阅读 0赞

**[https://leetcode-cn.com/problems/sum-of-two-integers/comments/][https_leetcode-cn.com_problems_sum-of-two-integers_comments]**  
**两数直接异或是无进位的加法器 得到A**  
**两数直接做与操作是得到各个位的进位B**  
**将A与B的二倍（左移一位 因为进位是要和前一位相加）再进行这样操作，直到进位为0**

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

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0wxNTU4MTk4NzI3_size_16_color_FFFFFF_t_70]

\*\* AddressSanitizer 工具，会对有符号数的左移位操作做保护，强制转成无符号数做移位可绕过。\*\*  
**负数左移的时候会出问题但是编译的时候不报错**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0wxNTU4MTk4NzI3_size_16_color_FFFFFF_t_70 1]

#include <iostream>
    using namespace std;
    
    
    class Solution { 
    public:
        int getSum(int a, int b) { 
            while (b) { 
                auto c = ((unsigned int)a & b) << 1; // 防止 AddressSanitizer 对有符号左移的溢出保护处理
                a = a ^ b;
                b = c;
            }
            return a;
        }
    };
    
    int main()
    { 
        Solution Solution1;
        cout<<Solution1.getSum(-1,1)<<endl;
        return 0;
    }

[https_leetcode-cn.com_problems_sum-of-two-integers_comments]: https://leetcode-cn.com/problems/sum-of-two-integers/comments/
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0wxNTU4MTk4NzI3_size_16_color_FFFFFF_t_70 1]: /images/20220217/490b0179f55e4aee9dd773e38b8e985e.png