LeetCode 231. Power of Two

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

update v2.0:
class Solution {
public:
    bool isPowerOfTwo(int n) {
        if(n <= 0)
            return false;
        return pow(2, (round)(log(n) / log(2))) == n;
    }
};


//如果没有考虑n <= 0就会超时。。
class Solution {
public:
    bool isPowerOfTwo(int n) {
        if(n <= 0)
            return false;
        while(n != 1) {
            if(n % 2 == 0) {
                n = n / 2;
            } else {
                return false;
            }
        }
        return true;
    }
};

update v2.0:

class Solution {

public:

bool isPowerOfTwo(int n) {

if(n <= 0)

return false;

return pow(2, (round)(log(n) / log(2))) == n;

}

};

//如果没有考虑n <= 0就会超时。。

class Solution {

public:

bool isPowerOfTwo(int n) {

if(n <= 0)

return false;

while(n != 1) {

if(n % 2 == 0) {

n = n / 2;

} else {

return false;

}

return true;

}

};

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