Day 43 of DSA Problem Solving

Q1. Power of Two

Given an integer n, return true if it is a power of two. Otherwise, return false.

An integer n is a power of two, if there exists an integer x such that n == 2x.

Example

Input: n = 1
Output: true
Explanation: 20 = 1

Input: n = 16
Output: true
Explanation: 24 = 16

Code

/**
 * @param {number} n
 * @return {boolean}
 */


var isPowerOfTwo = function(n) {

    if (n < 1) return false;     
    if (n === 1) return true;    
    if (n % 2 !== 0) return false; 

  return isPowerOfTwo(n/2)

};

Q2. Power of Four

Given an integer n, return true if it is a power of four. Otherwise, return false.

An integer n is a power of four, if there exists an integer x such that n == 4x.

Example

Input: n = 16
Output: true

Input: n = 5
Output: false

Code

/**
 * @param {number} n
 * @return {boolean}
 */
var isPowerOfFour = function(n) {

    if (n < 1) return false;     
    if (n === 1) return true;    
    if (n % 2 !== 0) return false; 

  return isPowerOfFour(n/4)

};

Q3. Power of Three

Given an integer n, return true if it is a power of three. Otherwise, return false.

An integer n is a power of three, if there exists an integer x such that n == 3x.

Example

Input: n = 27
Output: true
Explanation: 27 = 33

Input: n = 0
Output: false
Explanation: There is no x where 3x = 0.

Code

/**
 * @param {number} n
 * @return {boolean}
 */

var isPowerOfThree = function(n) {
    if(n === 1) return true;
    if(n === 0) return false


   return isPowerOfThree(n/3)
};