using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

​

/*

 * Given a stream of characters (e.g. acacabcatghhellomvnsdb) and a list of words 

 * (e.g. ["aca","cat","hello","world"] ) find and display count of each and 

 * every word once the stream ends.

 * (Like : "aca" : 2 , "cat" : 1 , "hello" : 1 , "world" : 0 ).

 * 

*/

​

namespace Set42_Counting_words

{

    public class Program

    {

        public static void Main(string[] args)

        {

            string streamOfCharacters = "acacabcatghhellomvnsdb";

​

            List<string> listOfWords = new List<string>()

            {

                "aca","cat","hello","world"

            };

​

            findWithRegExp(streamOfCharacters, listOfWords);

            Console.WriteLine("----------------------------------------------------");

            findWithBruteForce(streamOfCharacters, listOfWords);

            Console.ReadKey();

​

        }

​

        static void findWithRegExp(string streamOfCharacters, List<string> listOfWords) {

            foreach (string word in listOfWords)

            {

                Console.WriteLine("{0} : {1}", word, Regex.Matches(streamOfCharacters, "(?=(" + word + ")).").Count);

            }

        }

​

        static void findWithBruteForce(string streamOfCharacters, List<string> listOfWords) {

            Dictionary<string, int> dictOfWords = new Dictionary<string, int>();

            foreach (string word in listOfWords)

                if (!dictOfWords.ContainsKey(word))

                    dictOfWords.Add(word, 0);

​

            for (int i = 0; i < streamOfCharacters.Length - 1; i++)

            {

                foreach (string word in listOfWords)

                    if (streamOfCharacters[i] == word[0])

                    {

                        if (checkWordIncluding(streamOfCharacters, i, word))

                            dictOfWords[word]++;

                    }

            }

​

            foreach (KeyValuePair<string, int> wordWithStat in dictOfWords)

                Console.WriteLine("{0} : {1}", wordWithStat.Key, wordWithStat.Value);

        }

​

        static bool checkWordIncluding(string streamOfCharacters, int startPos, string checkingWord)

        {

            int j = 0;

            for (int i = startPos; i < streamOfCharacters.Length-1; i++)

            {

                if (j == checkingWord.Length - 1) // конец слова

                    if (streamOfCharacters[i] == checkingWord[j])

                        return true;

                if (streamOfCharacters[i] != checkingWord[j])

                    return false;

                j++;

            }

​

            return false;

        }

    }

}

​