腾讯//2的幂

给定一个整数，编写一个函数来判断它是否是 2 的幂次方。

示例 1:

输入: 1
输出: true
解释: 20 = 1

示例 2:

输入: 16
输出: true
解释: 24 = 16

示例 3:

输入: 218
输出: false
class Solution {
    public boolean isPowerOfTwo(int n) {
        if(n == 0)
            return false;
        while(n!=1){
            if(n%2==0)
                n/=2;
            else
                return false;
        }
        return true;
    }
}
class Solution {
public:
    bool isPowerOfTwo(int n) {
       if (n<=0) return false;
        return  ((n&(n-1))==0);
    }
};

Code

 

posted @ 2018-10-26 20:31  strawqqhat  阅读(206)  评论(0)  编辑  收藏  举报
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