02. Command Interpreter

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace Command_Interpreter
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> list = Console.ReadLine()
                .Split(new char[] { ' ', '\t', '\r', '\n' },StringSplitOptions.RemoveEmptyEntries)
                .ToList();

            string input = Console.ReadLine();
            while (input != "end")
            {
                int start = 0;
                int count = 0;
                string[] tokens = input
                    .Split(new char[] { ' ', '\t', '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries)
                    .ToArray();
                switch (tokens[0])
                {
                    case "reverse":
                        start = int.Parse(tokens[2]);
                        count = int.Parse(tokens[4]);
                        Reverse(list,start,count);
                        break;
                    case "sort":
                        start = int.Parse(tokens[2]);
                        count = int.Parse(tokens[4]);
                        Sort(list, start, count);
                        break;
                    case "rollLeft":
                        count = int.Parse(tokens[1]);
                        rollLeft(list, count);
                        break;
                    case "rollRight":
                        count = int.Parse(tokens[1]);
                        rollRight(list, count);
                        break;
                    default:
                        break;
                }
                input = Console.ReadLine();
            }
            Console.WriteLine("[{0}]",string.Join(", ",list));
        }
        private static void Reverse (List<string> list, int start, int count)
        {
            if (start < 0 || start >= list.Count || count < 0 || start + count - 1 >= list.Count)
            {
                Console.WriteLine("Invalid input parameters.");
                return;
            }
            list.Reverse(start, count);
        }
        private static void Sort (List<string> list, int start, int count)
        {
            if (start < 0 || start >= list.Count || count < 0 || start + count - 1 >= list.Count)
            {
                Console.WriteLine("Invalid input parameters.");
                return;
            }
            list.Sort(start, count, StringComparer.InvariantCulture);
        }
        private static void rollLeft (List<string> list, int count)
        {
            if (count < 0)
            {
                Console.WriteLine("Invalid input parameters.");
                return;
            }
            int pos = count % list.Count;
            for (int i = 0; i < pos; i++)
            {
                list.Add(list[0]);
                list.Remove(list[0]);
            }
        }
        private static void rollRight (List<string> list, int count)
        {
            if (count < 0)
            {
                Console.WriteLine("Invalid input parameters.");
                return;
            }
            int pos = count % list.Count;
            for (int i = 0; i < pos; i++)
            {
                list.Insert(0, list[list.Count - 1]);
                list.RemoveAt(list.Count - 1);
            }
        }
    }
}