---
tags: LeetCode
---

# 371. 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

---
輸入範本如下

public class Solution {
    public int GetSum(int a, int b) {
        
    }
}

自我限制 , 不准使用 Linq 的 Sum 方法(雖然實際上 Sum 也有使用 + 號運算子實作XD)

40 ms	15.5 MB
You are here!
Your runtime beats 67.46 % of csharp submissions.
public int GetSum(int a, int b) => new int[] { a, b }.Sum();

### 直覺想法
1. 非地回解法

    36 ms	14.6 MB
    You are here!
    Your runtime beats 92.82 % of csharp submissions.
    public int GetSum(int a, int b)
    {
        while (b != 0)
        {
            int carry = (a & b) << 1;
            int sum = a ^ b;
            a = sum;
            b = carry;
        }
        return a;
    }

2. 地回解法

    36 ms	14.6 MB
    You are here!
    Your runtime beats 92.82 % of csharp submissions.
    public int GetSum(int a, int b)
    {
         if (b == 0)
         {
              return a;
         }
         int carry = (a & b) << 1;
         int sum = a ^ b;
         return GetSum(sum, carry);
    }

### 參考資源
[LeetCode 371. Sum of Two Integers](https://skyyen999.gitbooks.io/-leetcode-with-javascript/content/questions/371md.html)

### Thank you!

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- [GitHub](https://github.com/s0920832252)
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