OOP 1

using System.Collections.Generic;
using System.Linq;

namespace TextAnalysis
{
    static class SentencesParserTask
    {
        public static List<List<string>> ParseSentences(string text)
        {
            char[] expressionsForLines = { '.', '!', '?', ';', ':', '(', ')' };
            var sentencesList = new List<List<string>>();
            List<string> lines = text.Split(expressionsForLines).ToList();
            int lineCounter = 0;
            foreach (var line in lines)
            {
                bool lineIsEmpty = true;
                int wordCounter = 0;
                int charCounter = 0;

                for (int i = 0; i < line.Length; i++)
                {
                    if ((char.IsLetter(line[i])) || (line[i] == '\''))
                    {
                        lineIsEmpty = false;
                        charCounter = i;
                        break;
                    }
                }
                if (lineIsEmpty) continue;
                sentencesList.Add(new List<string>());
                bool wordIsEmpty = true;
                for (int i = charCounter; i < line.Length; i++)
                {
                    if ((char.IsLetter(line[i])) || (line[i] == '\''))
                    {
                        if (sentencesList[lineCounter].Count == wordCounter)
                        {
                            sentencesList[lineCounter].Add("");
                            wordIsEmpty = false;
                        }
                        sentencesList[lineCounter][wordCounter] += char.ToLower(line[i]);
                    }
                    else if (wordIsEmpty)
                    {
                        continue;
                    }
                    else
                    {
                        wordCounter++;
                        wordIsEmpty = true;
                    }
                }
                lineCounter++;
            }
            return sentencesList;
        }
    }
}