leetcode Power of Two位运算

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.

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可以直接做：

class Solution {
public:
	bool isPowerOfTwo(int n) {
		if (n < 1) return false;
		int res;
		while (n>0)
		{
			res = n % 2;
			if (res != 0)
			{
				if (n == 1)
					return true;
				else
					return false;
			}
			n = n / 2;
		}
	}
};

也可以用位运算：

class Solution {
public:
	bool isPowerOfTwo(int n) {
		if (n < 1) return false;
	    return !(n&(n-1));
	}
};