2 to the power of N

Here is a one-liner statement to check if a given integer is of 2 to the power of N.

  public static boolean twoPowerN(int x){  
    return ((x & -x) == x) ? true : false;  
  }

You may try the method using this test case:
System.out.println(twoPowerN((int) Math.pow(2, 8)));

Basically it returns true for all integers 2powN, for example 2^100 or 2^7 or 2^33. A false will be returned for values other than 2powN. Well, that's the purpose of this method anyway (to check if a method is 2 to the power of N), right? :)

Have a good day everyone!

Swapping 2 Integers

I believe many of us out there came across, at least once in their lifetime, the problem to swap two numbers. Here are the three sample solutions that I could think to swap two numbers.
Solution A:

  temp = a;
  a = b;
  b = temp;

Solution A introduces an additional auxiliary variable called "temp" in the code to hold one of the values (either a or b) which increases the footprint of the compiled class.
Solution B:

  a = a ^ b;
  b = b ^ a;
  a = a ^ b;

Solution B on the other side swaps two numbers using bitwise operation. The XOR (Exclusive OR) is introduced in this code.
Solution C:

  a = a + b;
  b = a - b;
  a = a - b; 

Last but not least, Solution C swaps two numbers using arithmetic operations, both addition and subtraction.
Conclusion: In terms of speed, I would personally rank Solution B being the fastest, Solution C the second fastest and Solution A the slowest. (B -> C -> A)