LeetCode 342. Power of Four

时间:2024-09-07 19:03:56

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example:
Given num = 16, return true. Given num = 5, return false.

Follow up: Could you solve it without loops/recursion?

先说明用循环:

如下

class Solution {
public:
bool isPowerOfFour(int num) {
if(num<)return false;
char position=-;
int i=;
while(i<=)
{
if(num&(<<(i)))
{
if(-!=position&&position!=i)
return false;
position=i;
}
++i;
}
if(position%)return false;
else return true;
}
};

然后我发现题目中提示,你可以不用循环或者递归吗?我就去搜寻了一下这个题目发现http://www.cnblogs.com/grandyang/p/5403783.html

发现第三种方法很巧妙