HackerRank - Funny String https://www.hackerrank.com/challenges/funny-string

funnyString.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FunnyString
{
    /*
     * Funny String
     * https://www.hackerrank.com/challenges/funny-string
     * Test Case 0: S0= "acxz" 
        |c−a|=2=|x−z| 
        |x−c|=21=|c−x| 
        |z−x|=2=|a−c| 
        We print Funny.
     * 
     * 
     * 
     */
    class Solution 
    {
        static void Main(string[] args)
        {
            string s1 = Console.ReadLine();
            int n = Convert.ToInt16(s1); 
            for(int i=0;i<n;i++)
            {
                string s = Console.ReadLine();
                string output = "Not Funny"; 
                if (isFunnyString(s))
                    output = "Funny";
                Console.WriteLine(output);               
            }
        }

        /*
         * string length >=2 
         * 
         */
        public static bool isFunnyString(string s)
        {
            if (s == null || s.Length == 0)
                return false;

            int l = s.Length; 
            
            for(int i=0; i<l/2; i++)
            {
                if (calValue(s, i, true) != calValue(s, i, false))
                    return false; 
            }
            return true; 
        }

        /*
         * Forward, i, i+1
         * Backward, i, i-1
         */
        private static int calValue(string s, int i, bool forward)
        {
            int l = s.Length;
            return forward ? (Math.Abs(s[i] - s[i + 1])) : (Math.Abs(s[l - 1 - i] - s[l - 2 - i])); 
        }
    }
}