Fano-Shenon

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

namespace Фано_Шеннон
{
    internal class Program
    {
        static void Main(string[] args)
        {
            double[] prob;
            char[] chars;
            string stroka = "";
            FanoShennon fs;
            Dictionary<char, string> dict = new Dictionary<char, string>();
            Dictionary<string, char> reversedict = new Dictionary<string, char>();
            using(var sr = new StreamReader("input.txt"))
            {
                string[] str = sr.ReadToEnd().Split('\n');
                int n = str.Length;
                prob = new double[str.Length-1]; chars = new char[str.Length-1];
                for (int i = 0; i < str.Length-1; i++)
                {
                    string[] vs = str[i].Split(new char[] {'\r', ' '});
                    prob[i] = double.Parse(vs[0]);
                    chars[i] = char.Parse(vs[1]);
                }
                stroka = str[str.Length-1];
                Console.WriteLine(stroka);
                fs = new FanoShennon(prob, chars);
                fs.Sort();
                fs.Fano(0,n-2);
                for (int i = 0; i < n-1; i++)
                {
                    dict.Add(fs.let[i], fs.Res[i]);
                    reversedict.Add(fs.Res[i], fs.let[i]);
                    Console.WriteLine(fs.let[i] + " " + fs.Res[i]);
                }

            }
            string codeStr = "";
            for (int i = 0; i < stroka.Length; i++)
            {
                codeStr += dict[stroka[i]];
            }
            Console.WriteLine(codeStr);
            double step = Math.Round((double)stroka.Length * 8 / codeStr.Length,4);
            Console.WriteLine($"Степень сжатия = {step}");

            string tempstr = "";
            string result = "";
            for (int i = 0; i < codeStr.Length; i++)
            {
                tempstr += codeStr[i];
                if(reversedict.ContainsKey(tempstr))
                {
                    result += reversedict[tempstr];
                    tempstr = "";
                }
            }
            Console.WriteLine(result);
            Console.ReadKey();
        }
    }
    class FanoShennon
    {

        public FanoShennon(double[] p, char[] letters)
        {
            prob = p;
            let = letters;
            Res = new string[prob.Length];
        }
        double[] prob;
        internal char[] let;
        internal string[] Res;

        double schet1 = 0;
        double schet2 = 0;

        public void Sort()
        {
            for (int i = 0; i < prob.Length; i++)
            {
                for (int j = 0; j < prob.Length - i - 1; j++)
                {
                    if (prob[j] < prob[j + 1])
                    {
                        char temp2;
                        double temp1 = 0;

                        temp1 = prob[j];
                        temp2 = let[j];
                        prob[j] = prob[j + 1];
                        let[j] = let[j + 1];
                        prob[j + 1] = temp1;
                        let[j + 1] = temp2;

                    }
                }
            }

        }
        int m;

        public int Delenie_Posledovatelnosty(int L, int R)
        {

            schet1 = 0;
            for (int i = L; i <= R - 1; i++)
            {
                schet1 = schet1 + prob[i];
            }

            schet2 = prob[R];
            m = R;
            while (schet1 >= schet2)
            {
                m = m - 1;
                schet1 = schet1 - prob[m];
                schet2 = schet2 + prob[m];
            }
            return m;

        }

        public void Fano(int L, int R)
        {
            int n;

            if (L < R)
            {

                n = Delenie_Posledovatelnosty(L, R);
                //Console.WriteLine(n);

                for (int i = L; i <= R; i++)
                {
                    if (i <= n) Res[i] += Convert.ToByte(0);
                    else Res[i] += Convert.ToByte(1);
                }

                Fano(L, n);
                Fano(n + 1, R);

            }
        }

    }
}