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; } 相关资源：敏捷开发V1.0.pptx