Algo. IsPalindrome

https://leetcode.com/problems/valid-palindrome/

my decision below

        static bool IsPalindrome(string s)
        {
            var alphaNum = GetAlphaNumFromString(s).ToLower();
            if (alphaNum == "")
                return true;
            var reversed = ReverseString(alphaNum);
            Console.WriteLine(alphaNum);
            Console.WriteLine(reversed);
            return alphaNum.Equals(reversed);
        }

        static string GetAlphaNumFromString(string s)
        {
            StringBuilder sb = new StringBuilder();
            foreach (var c in s)
                if (Char.IsLetterOrDigit(c))
                    sb.Append(c);

            return sb.ToString();
        }

        static string ReverseString(string s)
        {
            char[] charArray = s.ToCharArray();
            Array.Reverse(charArray);
            return new string(charArray);
        }