231. Power of Two

题目

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

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

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思路

判断一个数是否是2的指数，本质上就是判断此数是否是正数，且bit只有一个为1

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代码

class Solution {public:    bool isPowerOfTwo(int n) {        //判断入参是不是2的指数，就是二进制bit只有一个1        //题目转化为判断入参的bit是否是正数且只有一个1，        if(n <= 0)        {            return false;        }        return !(n&(n-1));    }};