Palindrome Number

palindromeNumber.js

/**
 * @param {number} x
 * @return {boolean}
 */
var isPalindrome = function(x) {
    if(x < 0) return false;
    
    function rec(num, rev = 0) {
        if(num == 0) return rev;
        return rec(Math.floor(num / 10), (rev * 10 + (num % 10)))
    }

    let rev = rec(x, 0);

    if(rev == x) return true;
    return false;
};

// If negative return false
// recursive function to reverse the number
// If reverse and given are same then return true, else return false

// Way to reverse number: 
//  1. Get number % 10 and store it in a variable 
//  2. Keep the floor value of number / 10
//  3. Repeat and add reverse * 10 plus the step 1 value

// Time: O(log(n))
// Space: O(1)