using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        /*

          ***********************************************************

          Finding patterns with more than one occurrences in a string.

          ***********************************************************

        */

        //Prompt user to enter a string from which we need to find patterns of more than one occurrences

        Console.WriteLine("Enter input string: ");

        string inputString = Console.ReadLine();

​

        //Input validations

        while (string.IsNullOrEmpty(inputString))

        {

            Console.WriteLine("Input string cannot be empty. Please enter input string to find patterns ");

            inputString = Console.ReadLine();

        }

​

​

        // Prompt user to enter the length of the pattern to find occurrences

        Console.WriteLine("Enter pattern length: ");

        int patternLength = 0;

​

        //Input validations

        while (!int.TryParse(Console.ReadLine(), out patternLength))

        {

            Console.WriteLine("Pattern length can only accept digits. Please enter valid number from 0-9 ");

        }

        List<string> reccursivePatterns = new List<string>();

        //store multiple occurrences of pattern of x length into a list

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

        {

​

            string pattern = inputString.Substring(i, patternLength);

            reccursivePatterns.Add(pattern);

​

        }

        //find number of pattern of x lenght occurrences

        var query = reccursivePatterns.GroupBy(x => x)

                    .Where(g => g.Count() > 1)

                    .Select(y => new { Pattern = y.Key, Counter = y.Count() })

                    .ToList();

​

        Console.WriteLine("Pattern :  Occurrence ");

        // display patterns and number of occurrences

        foreach (var q in query.ToList())

        {

            Console.WriteLine(q.Pattern + "\t : \t" + q.Counter);

        }

        /*

        *********************************************************************

        Program to ask user to find number of occurrences of selected pattern

        from a default pattern(This pattern can be changed by user).

        *********************************************************************

        */

        //store default string pattern to find occurrences

        string defaultInputString = "zf3kabxcde224lkzf3mabxc51+crsdtzf3nab=";

​

        Console.WriteLine("Default Pattern : " + defaultInputString);

        //Prompt user to enter a string to find patterns of more than one occurrences from default string or change the default string

        Console.WriteLine("Enter input string to search a pattern from default string or enter c to change the default string : " + defaultInputString );

​

        string inputStringForSearch = Console.ReadLine();

​

        // Input validations

        while (string.IsNullOrEmpty(inputStringForSearch))

        {

            Console.WriteLine("Input string cannot be empty. Please enter input string to find patterns ");

            inputStringForSearch = Console.ReadLine();

        }

        //Logic to change default string when user decides to change the default input string

        if (inputStringForSearch == "C" || inputStringForSearch == "c")

        {

            Console.WriteLine("Enter input string to change the default string : ");

            defaultInputString = Console.ReadLine();

​

            // Input validations

            while (string.IsNullOrEmpty(defaultInputString))

            {

                Console.WriteLine("Input string cannot be empty. Please enter input string to find patterns ");

                defaultInputString = Console.ReadLine();

            }

            Console.WriteLine("Enter input string to search a pattern from  : " + defaultInputString);

​

            inputStringForSearch = Console.ReadLine();

​

            // Input validations

            while (string.IsNullOrEmpty(inputStringForSearch))

            {

                Console.WriteLine("Input string cannot be empty. Please enter input string to find patterns ");

                inputStringForSearch = Console.ReadLine();

            }

        }

​

​

        // Find number of occurrences

        int patternLength1 = inputStringForSearch.Length;

​

​

        List<string> reccursivePatterns1 = new List<string>();

​

​

        for (int i = 0; i < defaultInputString.Length - patternLength1; i++)

        {

​

            //store multiple occurrences of pattern of x length into a list

            string pattern = defaultInputString.Substring(i, patternLength1);

            if (pattern == inputStringForSearch)

            {

                reccursivePatterns1.Add(pattern);

            }

​

        }

        //find number of pattern of x lenght occurrences

        var query1 = reccursivePatterns1.GroupBy(x => x)

            .Where(g => g.Count() > 1)

            .Select(y => new { Pattern = y.Key, Counter = y.Count() })

            .ToList();

​

        Console.WriteLine("Pattern :  Occurrence ");

        // display patterns and number of occurrences

        foreach (var q in query1.ToList())

        {

​

            Console.WriteLine(q.Pattern + "\t : \t" + q.Counter);

        }

    }

}