Leetcode does not add, subtract, multiply, divide, and calculate the number of 1 in binary

You cannot use addition, subtraction, multiplication and division , Then we can consider what we learned in introduction to computer ^( Exclusive or ） operation as well as &( And operation ）

According to the above ideas The code is as follows

class Solution {
public:
    int Add(int num1, int num2) {
             while(num2!=0){
                 int sum=num1^num2;
                 int add=(unsigned int )(num1&num2)<<1;
                 num1=sum;
                 num2=add;
                 
                 
                 
             }
        return num1;
    }
};

The second topic , It is still done by bit operation for example << Operator is to move binary bits to the left by one bit

  In binary numbers 1 The number of , We learned that Any number and decimal number 1 Meet each other , If the mantissa of this number is 0 be , The result is 0, If mantissa is 1 The result is 1

We can pass the 1 Of 32 position 2 Hexadecimal shift left , It can judge the given number 32 Whether the number of digits is 1 The situation of

The code is as follows

class Solution {
public:
     int  NumberOf1(int n) {
         int res=0;
         for(int i=0;i<=31;i++){
             if((n&(1<<i))!=0)
                 res++;
         }
         return res;
     }
};