RepeatingPatternLinq

namespace RepeatingPrattern
{
    using System;
    using System.Linq;

    public class GoogleSolutuion
    {
        public static void Main()
        {
            string input = Console.ReadLine();

            var result = FindPattern(input);

            if (result == null)
            {
                result = input;
            }

            Console.WriteLine(result);
        }

        public static string FindPattern(string text)
        {
            if (text == null)
            {
                return null;
            }

            return Enumerable.Range(1, text.Length / 2)
                .Where(n => text.Length % n == 0)
                .Select(n => text.Substring(0, n))
                .Where(pattern => Enumerable.Range(0, text.Length / pattern.Length)
                    .SelectMany(i => pattern)
                    .SequenceEqual(text))
                .FirstOrDefault();
        }
    }
}