231. Power of Two

题目描述

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

Qiang的思路

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        if n < 1:
            return False
        while n > 1:
            m = n>>1
            if m<<1 != n:
                return False
            n = m
        return True

class Solution {
public:
    bool isPowerOfTwo(int n) {
        if(n<1)
            return false;
        while(n>1){
            if(n>>1<<1 != n)
                return false;
            n=n>>1;
        }
        return true;
    }
};