LeetCode --- 231. Power of Two

231. Power of Two

Difficulty: Easy

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

Example 1:

Input: 1
Output: true 
Explanation: 20 = 1

Example 2:

Input: 16
Output: true
Explanation: 24 = 16```

**Example 3:**

Input: 218
Output: false```

Solution

Language: C++

思路

如果n大於0，且n的二進制只有1位數字爲1，返回true。否則返回0；
如果n只有一位1，n & (n-1)的結果爲0。

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