O(1) Check Power of 2

Using O(1) time to check whether an integer n is a power of 2.

Have you met this question in a real interview?

Yes

Example

For n=4, return true;

For n=5, return false;

Challenge

O(1) time

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class Solution {
    /*
     * @param n: An integer
     * @return: True or false
     */
    public boolean checkPowerOf2(int n) {
        // write your code here
        if(n < 0) return false;
        if(n == 0) return false;
        return (n & (n - 1)) == 0;
    }
};