LeetCode Q231: Power of Two

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


Solution 1:

	class Solution {
	public:
	bool isPowerOfTwo(int n) {
	double num = log2(n);
	return n==0? false:num==round(num);
	}
	};

view raw Q231PowerOfTwo.cpp hosted with ❤ by GitHub

Solution 2:

	class Solution {
	public:
	bool isPowerOfTwo(int n) {
	return n > 0 && !(n&(n-1));
	}
	};

view raw Q231-2.cpp hosted with ❤ by GitHub

Round 2 solution: Need to take care negtive number and zero:

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

view raw Q231Rnd2.cpp hosted with ❤ by GitHub