231. Power of Two

Given an integer, write a function to determine if it is a power of two.

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

public class Solution {
    public boolean isPowerOfTwo(int n) {  
        if(n<=0)  
            return false;  
        return (n&(n-1))==0;  
    }  
}