using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        // Modify these user inputs to find patterns

        string inputText = "zf3kabxcde224lkzf3mabxc51+crsdtzf3nab=";

        int patternLength = 3;

        // Execute pattern matching search

        Dictionary<string, int> results = FindPatterns(inputText, patternLength);   

        PrintPatterns(results);

    }

    /// <summary>

    /// Find all patterns of a specific length from a given input string.

    /// </summary>

    /// <param name="input">Text to be searched for patterns</param>

     ///<param name="patternLength">Specific length of patterns</param> 

    public static Dictionary<string, int> FindPatterns(string inputText, int patternLength)

    {

        Dictionary<String, int> dict = new Dictionary<String, int>();

        // Validate that the input values are appropriate

        if (inputText == null || patternLength <= 0 || patternLength > inputText.Length)

            return dict;

​

        // Find the number of occurences of each substring

        for (int i = 0; i <= inputText.Length - patternLength; i++)

        {

            string subString = inputText.Substring(i, patternLength);

            if (dict.ContainsKey(subString))

                dict[subString] += 1;

            else

                dict.Add(subString, 1);

        }

        // Clean the dictionary to only include substrings that are patterns

        foreach(var item in dict.Where(kvp => kvp.Value == 1).ToList())

            dict.Remove(item.Key);

        return dict;

    }

    /// <summary>

    /// Print all patterns found with the corresponding number of occurrences.

    /// </summary>

    /// <param name="dict">Collection of patterns and the number of occurrences</param> 

    public static void PrintPatterns(Dictionary<string, int> dict)

    {

        // Input validation

        if (dict == null)

            return;

        // No patterns found

        if (dict.Count() == 0)

        {

            Console.WriteLine("No patterns were found.");

            return;

        }

        // Patterns found

        foreach (KeyValuePair<string, int> kvp in dict)

            Console.WriteLine("Pattern \"{0}\" occurred {1} times.", kvp.Key, kvp.Value);   

    }

}