Finding the ranking of a word (permutations) with duplicate letters

Question

I\'m posting this although much has already been posted about this question. I didn\'t want to post as an answer since it\'s not working. The answer to this post (Finding th

Answer 1

@Dvaid Einstat, this was really helpful. It took me a WHILE to figure out what you were doing as I am still learning my first language(C#). I translated it into C# and figured that I'd give that solution as well since this listing helped me so much!

Thanks!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;

namespace CsharpVersion
{
    class Program
    {
        //Takes in the word and checks to make sure that the word
        //is between 1 and 25 charaters inclusive and only
        //letters are used
        static string readWord(string prompt, int high)
        {
            Regex rgx = new Regex("^[a-zA-Z]+$");
            string word;
            string result;
            do
            {
                Console.WriteLine(prompt);
                word = Console.ReadLine();
            } while (word == "" | word.Length > high | rgx.IsMatch(word) == false);
            result = word.ToUpper();
            return result;
        }

        //Creates a sorted dictionary containing distinct letters 
        //initialized with 0 frequency
        static SortedDictionary Counter(string word)
        {
            char[] wordArray = word.ToCharArray();
            int len = word.Length;
            SortedDictionary count = new SortedDictionary();
           foreach(char c in word)
           {
               if(count.ContainsKey(c))
               {
               }
               else
               {
                   count.Add(c, 0);
               }

           }
           return count;
        }

        //Creates a factorial function
        static int Factorial(int n)
        {
            if (n <= 1)
            {
                return 1;
            }
            else
            {
                return n * Factorial(n - 1);
            }
        }
        //Ranks the word input if there are no repeated charaters 
        //in the word
        static Int64 rankWord(char[] wordArray)
        {
            int n = wordArray.Length; 
            Int64 rank = 1; 
            //loops through the array of letters
            for (int i = 0; i < n-1; i++) 
            { 
                int x=0; 
            //loops all letters after i and compares them for factorial calculation
                for (int j = i+1; j wordArray[j]) 
                    {
                        x++;
                    }
                }
                rank = rank + x * (Factorial(n - i - 1)); 
             }
            return rank;
        }

        //Ranks the word input if there are repeated charaters
        //in the word
        static Int64 rankPerm(String word) 
        {
        Int64 rank = 1;
        Int64 suffixPermCount = 1;
        SortedDictionary counter = Counter(word);
        for (int i = word.Length - 1; i > -1; i--) 
        {
            char x = Convert.ToChar(word.Substring(i,1));
            int xCount;
            if(counter[x] != 0) 
            {
                xCount = counter[x] + 1; 
            }
            else
            {
               xCount = 1;
            }
            counter[x] = xCount;
            foreach (KeyValuePair e in counter)
            {
                if (e.Key < x)
                {
                    rank += suffixPermCount * e.Value / xCount;
                }
            }

            suffixPermCount *= word.Length - i;
            suffixPermCount /= xCount;
        }
        return rank;
        }




        static void Main(string[] args)
        {
           Console.WriteLine("Type Exit to end the program.");
           string prompt = "Please enter a word using only letters:";
           const int MAX_VALUE = 25;
           Int64 rank = new Int64();
           string theWord;
           do
           {
               theWord = readWord(prompt, MAX_VALUE);
               char[] wordLetters = theWord.ToCharArray();
               Array.Sort(wordLetters);
               bool duplicate = false;
               for(int i = 0; i< theWord.Length - 1; i++)
               {
                 if(wordLetters[i] < wordLetters[i+1])
                 {
                     duplicate = true;
                 }
               }
               if(duplicate)
               {
               SortedDictionary counter = Counter(theWord);
               rank = rankPerm(theWord);
               Console.WriteLine("\n" + theWord + " = " + rank);
               }
               else
               {
               char[] letters = theWord.ToCharArray();
               rank = rankWord(letters);
               Console.WriteLine("\n" + theWord + " = " + rank);
               }
           } while (theWord != "EXIT");

            Console.WriteLine("\nPress enter to escape..");
            Console.Read();
        }
    }
}