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

    Example 1:

    1. Input: 1
    2. Output: true 
    3. Explanation: 20 = 1

    Example 2:

    1. Input: 16
    2. Output: true
    3. Explanation: 24 = 16

    Example 3:

    1. Input: 218
    2. Output: false
    1. /**
    2.  * @param {number} n
    3.  * @return {boolean}
    4.  */
    5. var isPowerOfTwo = function(n) {
    6.     if (n < 1) {
    7.         return false;
    8.     }
    9.     while(n > 1) {
    10.         if (parseInt(n % 2) !== 0) {
    11.             return false;
    12.         }
    13.         n = parseInt(n /2);
    14.     }
    15.     return true;
    16. };
    /**
 * @param {number} num
 * @return {boolean}
 */
var isPowerOfTwo = function(num) {
    if (num < 1) {
        return false;
    }
    const bits = num.toString(2);
    for (let i = 1; i < bits.length; i++) {
      if (bits[i] !== '0') {
        return false;
      }
    }
    return true;
};

    /**
 * @param {number} n
 * @return {boolean}
 */
var isPowerOfTwo = function(n) {
    if (n < 1) {
        return false;
    }
    return (n & (n - 1)) === 0;
};