231. Power of Two

题目：

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

链接： http://leetcode.com/problems/power-of-two/

2/28/2017

看别人的。看来要注意各种比特运算。

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