Power of Four

1. Description

2. Solution

• Version 1

代码语言：javascript复制

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

• Version 2

代码语言：javascript复制

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

• Version 3

代码语言：javascript复制

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

version

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