using System;

public class Program

{

    public static void Main()

    {

        string s1 = "pale";

        string s2 = "ple";

        bool result = AreOneEditAway(s1, s2);

        Console.WriteLine($"Are \"{s1}\" and \"{s2}\" one edit or zero edits away? {result}");

        s1 = "pales";

        s2 = "pale";

        result = AreOneEditAway(s1, s2);

        Console.WriteLine($"Are \"{s1}\" and \"{s2}\" one edit or zero edits away? {result}");

        s1 = "pale";

        s2 = "bale";

        result = AreOneEditAway(s1, s2);

        Console.WriteLine($"Are \"{s1}\" and \"{s2}\" one edit or zero edits away? {result}");

        s1 = "pale";

        s2 = "bake";

        result = AreOneEditAway(s1, s2);

        Console.WriteLine($"Are \"{s1}\" and \"{s2}\" one edit or zero edits away? {result}");

    }

    static bool AreOneEditAway(string s1, string s2)

    {

        if (Math.Abs(s1.Length - s2.Length) > 1)

        {

            return false;

        }

​

        if (s1.Length == s2.Length)

        {

            return OneReplaceAway(s1, s2);

        }

​

        if (s1.Length + 1 == s2.Length)

        {

            return OneInsertAway(s1, s2);

        }

​

        if (s1.Length == s2.Length + 1)

        {

            return OneInsertAway(s2, s1);

        }

​

        return false;

    }

​

    static bool OneReplaceAway(string s1, string s2)

    {

        bool foundDifference = false;

        for (int i = 0; i < s1.Length; i++)

        {

            if (s1[i] != s2[i])

            {

                if (foundDifference)

                {

                    return false;

                }

                foundDifference = true;

            }

        }

        return true;

    }

​

    static bool OneInsertAway(string s1, string s2)

    {

        int index1 = 0;

        int index2 = 0;

        while (index1 < s1.Length && index2 < s2.Length)

        {

            if (s1[index1] != s2[index2])

            {

                if (index1 != index2)

                {

                    return false;

                }

                index2++;

            }

            else

            {

                index1++;

                index2++;

            }

        }

        return true;

    }

}