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.
2的次方的特点是只有一位是1，因此n&(n-1)==0则证明只有一个1.
public class Solution {
public boolean isPowerOfTwo(int n) {
if (n <= 0) {
return false;
}
return (n & (n-1)) == 0;
}
}
原文：http://www.cnblogs.com/shini/p/4637976.html