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;
    }
};

1. 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
    }
}

1. 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;
    }
}

1. 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]));
    }
};

1. 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;
}