using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

      var array = new[]

      {

         "Bunny -vs- Kitten",

         "Bunny -vs- Camel",

         "Lion -vs- Camel",

         "Hippo -vs- Piranha",

         "Kitten -vs- Bunny"

      };

​

      static (string key, string value) Process(string value)

      {

         var split = value.Split("-vs-")

            .Select(x => x.Trim())

            .OrderBy(x => x)

            .ToArray();

         return (string.Concat(split), value);

      }

​

      var items = array

         .Select(Process)

         .ToArray();

​

      var dict = items.GroupBy(x => x.key)

         .Select((x, i) => (x.Key, id: i + 1))

         .ToDictionary(x => x.Key, x => x.id);

​

      var results = items.Select(x => $"{dict[x.key]}: {x.value}");

​

      foreach (var result in results)

         Console.WriteLine(result);

​

    }

}