Solving Jumble Puzzles Using a Recursive Algorithm

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

[assembly: CLSCompliant(true)]
namespace Unscramble
{
    class Permutations
    {
        private int itemLevel = -1;
        private int numOfItems;
        private int permCount;
        private int[] permutation = new int[0];
        private char[] inputCharSet;
        private List<string> permList = new List<string>();
        object missing = System.Reflection.Missing.Value;

        // Called directly w/o using directive to prevent ambiguity
        // with System.Windows.Forms.Application object
        Microsoft.Office.Interop.Word.Application wordApp =
            new Microsoft.Office.Interop.Word.Application();

        ProgressBar pgProgress = (ProgressBar)Form1
            .ActiveForm.Controls["pbProgress"];

        /// <summary>
        /// Convert input string to character array
        /// </summary>
        /// <param name="inputString">User input string</param>
        public void MakeCharArray(string inputString)
        {
            inputCharSet = inputString.ToCharArray();
            numOfItems = inputCharSet.Length;
            Array.Resize(ref permutation, numOfItems);
        }

        /// <summary>
        /// Recursive Algorithm Source:
        /// A. Bogomolny, Counting And Listing All Permutations 
        /// from Interactive Mathematics Miscellany and Puzzles
        /// http://www.cut-the-knot.org/do_you_know/AllPerm.shtml,
        /// Accessed 11 June 2009
        /// </summary>
        /// <param name="position"></param>
        public void Recursion(int position)
        {
            itemLevel++;
            permutation.SetValue(itemLevel, position);
            if(itemLevel == numOfItems)
            {
                AddPermutation(permutation);
            }
            else
            {
                for(int currentPosition = 0; currentPosition < numOfItems;
                    currentPosition++)
                {
                    if(permutation[currentPosition] == 0)
                    {
                        Recursion(currentPosition);
                    }
                }
            }
            itemLevel--;
            permutation.SetValue(0, position);
        }

        /// <summary>
        /// Code Source (AddItem()):
        /// A. Bogomolny, Counting And Listing All Permutations
        /// from Interactive Mathematics Miscellany and Puzzles
        /// http://www.cut-the-knot.org/do_you_know/AllPerm.shtml,
        /// Accessed 11 June 2009
        /// </summary>
        /// <param name="currentPermutation">A permutation</param>
        private void AddPermutation(int[] currentPermutation)
        {
            string tempPermString = "";
            foreach(int item in currentPermutation)
            {
                tempPermString += inputCharSet.GetValue(item - 1);
                // Build string permutation from position permutation
            }
            permList.Add(tempPermString);
            permCount++;
        }

        /// <summary>
        /// Call Microsoft Word 11.0 Object Library 
        /// to check spelling of each permutation 
        /// </summary>
        /// <param name="theWord">Permutation to check</param>
        /// <returns>Is it a word?</returns>
        private bool CheckTheSpelling(string theWord)
        {
            pgProgress.Increment(1);
            bool result = false;
            try
            {
                if(wordApp.CheckSpelling(theWord, ref missing,
                    ref missing, ref missing, ref missing,
                    ref missing, ref missing, ref missing,
                    ref missing, ref missing, ref missing,
                    ref missing, ref missing) == true)
                {
                    result = true;
                }
                else
                {
                    result = false;
                }
            }
            catch(Exception)
            {
                wordApp.Quit(ref missing, ref missing, ref missing);
            }
            return result;
        }

        /// <summary>
        /// Format list of permutation as string for output to UI
        /// </summary>
        /// <returns>Results to UI</returns>
        public string OutputPermutations()
        {
            //Count all
            int allPermCount = permList.Count();
            var permListTrue = permList.Distinct();
            //Count distinct
            int uniquePermCount = permListTrue.Count();
            pgProgress.Maximum = uniquePermCount;

            permListTrue = permListTrue
                .Where(perm => CheckTheSpelling(perm) == true)
                .OrderBy(perm => perm);
            var permListFalse = permList
                .Distinct()
                .Except(permListTrue)
                .OrderBy(perm => perm);

            //Count answers
            int answersFound = permListTrue.Count();

            StringBuilder tempDisplay = new StringBuilder();

            try
            {
                foreach(string permutation in permListTrue)
                {
                    tempDisplay.AppendLine(permutation + " (true)");
                }
                tempDisplay.AppendLine("-------------------");
                foreach(string permutation in permListFalse)
                {
                    tempDisplay.AppendLine(permutation + " (false)");
                }
                tempDisplay.AppendLine("-------------------");
                tempDisplay.AppendLine("Total Permutations: " +
                    allPermCount.ToString());
                tempDisplay.AppendLine("Unique Permutations: " +
                    uniquePermCount.ToString());
                tempDisplay.AppendLine("Words Found: " + answersFound);
            }
            catch(Exception ex)
            {
                return ex.ToString();
            }
            finally
            {
                wordApp.Quit(ref missing, ref missing, ref missing);
            }
            return tempDisplay.ToString();
        }
    }
}