位运算中可以使用的三个技巧

1. x & (-x) to keep the rightmost 1-bit and to set all the others bits to zero.
   application:

• x&(-x)==x check if x is power of 2, pay attention to potentially overflow of -x

2. x & (x - 1) set the rightmost 1 bit as 0.
   application:

• x&(x - 1)==0 check if x is power of 2

3. x % 2 or x & 1 to retrive the right most bit