Leetcode 342. Power of Four

文章作者：Tyan
博客：noahsnail.com  |  优快云  |  简书

1. Description

2. Solution

• Version 1

class Solution {
public:
    bool isPowerOfFour(int num) {
        return !(num & (num - 1)) && (num & 0x55555555);
    }
};

• Version 2

class Solution {
public:
    bool isPowerOfFour(int num) {
        return num > 0 && (num & (num - 1)) == 0 && (num - 1) % 3 == 0;
    }
};

• Version 3

class Solution {
public:
    bool isPowerOfFour(int num) {
        return fmod(log10(num) / log10(4), 1) == 0;
    }
};

Reference

1. https://leetcode.com/problems/power-of-four/description/