Leetcode Power of Two

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

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Java code:（两种方法，第二种方法很妙，用到了bit wise ）

第二种方法解题思路：

如果一个整数是2的幂，那么它的二进制形式最高位为1，其余各位为0

等价于：n & (n - 1) = 0，且n > 0

/*
* 1 = 2^0, true
* */
public class PowerOfTwo {
    public static void main(String[] args) {
        int x =1023;
        boolean y = isPowerOfTwo(x);
        System.out.println(y);
    }

    /*
    * method1
    */
    public static boolean isPowerOfTwo(int n) {
        if(n <= 0 ) {return false;}
        while(n %2 == 0 ) {
                n = n/2;
        }
        if(n==1) {return true;}
        return false;
    }

    /*
    * method2
    * */
    public static boolean isPowerOfTwo(int n) {
        int x = n & (n-1);
        return (n > 0) & (x==0);
    }
}

Reference:

1. http://bookshadow.com/weblog/2015/07/06/leetcode-power-of-two/