算法1.-不用加减乘除做加法

1. 位运算

   //链接：https://www.nowcoder.com/questionTerminal/59ac416b4b944300b617d4f7f111b215
   //来源：牛客网
   //Java
   public class Solution {
       public int Add(int num1,int num2) {
           while (num2!=0) {
               int temp = num1^num2;
               num2 = (num1&num2)<<1;
               num1 = temp;
           }
           return num1;
       }
   }

   //C++:
   class Solution {
   public        
       int Add(int num1, int num2)
       {
           return num2?Add(num1^num2,(num1&num2)<<1):num1;
       }
   };

2. 汇编

   //链接：https://www.nowcoder.com/questionTerminal/59ac416b4b944300b617d4f7f111b215
   //来源：牛客网
   int add(int a, int b)
   {
       _asm
       {
           MOV EAX, a
           MOV ECX, b
           ADD EAX, ECX
       }
   }

3. 自增自减

   //链接：https://www.nowcoder.com/questionTerminal/59ac416b4b944300b617d4f7f111b215
   //来源：牛客网
   
   public class Solution {
       public int Add(int num1,int num2) {
           if(num1>0){
               while(num1--!=0)
                   num2++;
           }
           else if(num1<0){
               while(num1++!=0)
                   num2--;
           }
           return num2;
       }
   }

4. 通过指针

   //链接：https://www.nowcoder.com/questionTerminal/59ac416b4b944300b617d4f7f111b215
   //来源：牛客网
   
   class Solution {
   public:
       int Add(int num1, int num2)
       {
           char* a = reinterpret_cast<char*>(num1);
           return reinterpret_cast<long>(&(a[num2]));
       }
   };

5. 通过函数

   public int Add(int num1, int num2) {
      return Integer.sum(num1, num2);
   }

   Integer.sum()源码

   public static int sum(int a, int b) {
           return a + b;
   }