Determining whether an integer power of 2

Subject description:

　　To a number N, determine whether it is a power of 2?

 

Solving direction : according to the characteristics of the binary, a method using a direct outcome of elimination.

Elimination of a law : N - 1 can make the least significant bit of the N 1 to 0, so the least significant bit is a 0 per after 1, so N & (N - 1) (core) can eliminate a minimum of 1.

Problem solution idea: the power of two since the binary representation of only a 1, so the use of an elimination method, the result is necessarily 0.

Code:

// elimination method for solving whether it is a power of two 
    public  static Boolean F ( int N) {   // N input is not 0 
        IF ((N & (N- . 1 )) == 0 ) {
             return  to true ;
        }else{
            return false;
        }
    }