Sword refers to the number of 1 in offer-binary

Topic:

Implement a function, enter an integer, and output the number of 1 in the binary representation. As the binary of 9 is 1001, so input 9 output 2.

Solution one: Possible dead loops

int num1 (int n) {     int count =0;     while (n)     {         if (n&1) count++;         n=n>>1;      }      return count;}

The above function if you enter a negative number, if you have been doing the right operation, the final figure will become 0xFFFFFFFF and into a dead loop.

Solution Two: No dead cycle but low efficiency

int num1 (int n) {     int count =0;     unsigned int flag=1;     while (flag)     {         if (n&flag) count++;         flag=flag<<1;      }      return count;}

The number of cycles equals the number of digits in the integer binary, and 32-bit integers need to be looped 32 times.

Solution Three: There are several 1 only need to cycle several times

int num1 (int n) {     int count =0;     while (n)     {         ++count;         N= (n-1) &n;      }      return count;}

Sword refers to the number of 1 in offer-binary