[LeetCode]--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.

如果是power of two, 则2进制表达中,有且仅有一个1. 可以通过移位来数1的个数, 这里用了一个巧妙的办法, 即判断 N & (N-1) 是否为0.

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