using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

​

        Console.WriteLine("Hello World");

        string[] array = { "civic", "deified", "microsoft", "deleveled", "devoved", "dewed", null,

                            "level", "madam", "raceCar", "radar", "refer", "Net", "repaper",

                            "A", "", "Kris", "hello",

                            "reviver", "rotator", null,

                            "rotor", "sagas", "Palindrome", "solos", "sexes", "stats", "tenet",

                            };

        Console.WriteLine("Palindroms: " + string.Join("; ", array.Where(s => IsPalindrome(s))));

    }

    public static bool IsPalindrome(string phrase) 

    {

        // Good: Handle nulls and/or empty strings

        if (string.IsNullOrEmpty(phrase))

        {

            return false; //Bonus: Asks about sensible return type vs Exceptions

        }

        // Good: Asks about casing, punctuation, etc.

        phrase = phrase.ToLowerInvariant();

        //OK: Reverse string and compare 

        if (phrase.Reverse().ToString() != phrase) 

        {

            //return false;

        }

        //Good: Compare starting at ends and working inward

        for (int i=0; i <= phrase.Length / 2; i++) 

        {

            if (phrase[i] != phrase[phrase.Length - i - 1]) 

            { 

                //return false; 

            }

        }

​

        return true;

    }

}

​