C# 6 Aplicatie la siruri de caractere

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace CuvinteCareRimeaza

{

    class Program

    {

        /* se citeste un text, sa se scrie perechile de cuvintele care rimeaza (au ultimele 2 litere identice)

        apoi sa se scrie toate literele distincte si frecventele de aparitie

        metoda de rezolvare: intr-o unica parcurgere a sirului caracterele se numara intr-un tablou de structuri

        textul se reține intr-o variabila string apoi cuvintele se separa intr-un tablou de structuri

        care se parcurge apoi in 2 cicluri

        */

        struct caractere

        {

            public char caracter;

            public int contor;

        }

        struct cuvinte

        {

            public string cuvant;

            public bool folosit;

        }

        static caractere[] aparitii = new caractere[30];

        static cuvinte[] fraza = new cuvinte[300];

        static void Main(string[] args)

        {

            Console.Write("Introdu textul:");

            string text = Console.ReadLine(); //citeste text cu spatii pana la ENTER

            //intr-un singur ciclu numara caracterele distincte si separa cuvintele

            int l = text.Length;

            Console.WriteLine("lungime text={0}", l);

            int i = 0; // indice general in text

            int nrcar = 0; //contor in array aparitii

            int nrcuv = 0; //contor cuvinte in fraza

            int inceputCuvant = 0; //indice inceput cuvant

            bool spatii = true; //indicator ciclare spatii

            bool gasit = false; //indicator caracter gasit in vectorul aparitii

            while(i<l)

            {

                if (text[i] == ' ')

                {

                    if (!spatii)

                    {

                        spatii = true;

                        fraza[nrcuv].cuvant = text.Substring(inceputCuvant, i - inceputCuvant);

                        fraza[nrcuv].folosit = false;

                        nrcuv++;

                    }

                }

                else

                {

                    for (int k = 0; k <= nrcar; k++)

                    {

                        if (aparitii[k].caracter == text[i])

                        {

                            aparitii[k].contor++;

                            gasit = true;

                        }

                    }

                    if (!gasit)

                    {

                        aparitii[nrcar].caracter = text[i];

                        aparitii[nrcar].contor = 1;

                        nrcar++;

                    }

                    gasit = false;

                    if (spatii)

                    {

                        spatii = false;

                        inceputCuvant = i;

                    }

                }

                i++;

            }

            //trateaza ultima litera  (pentru  i=l-1)

            i--;

            for (int k = 0; k <= nrcar; k++)

            {

                if (aparitii[k].caracter == text[i])

                {

                    aparitii[k].contor++;

                    gasit = true;

                }

            }

            if (!gasit)

            {

                aparitii[nrcar].caracter = text[i];

                aparitii[nrcar].contor = 1;

                nrcar++;

            }

            i++;

            fraza[nrcuv].cuvant = text.Substring(inceputCuvant, i - inceputCuvant);

            fraza[nrcuv].folosit = false;

            nrcuv++;

            //afiseaza numarul de aparitii

            for (int j = 0; j <= nrcar-1; j++)

                Console.WriteLine("{0} de {1} ori", aparitii[j].caracter, aparitii[j].contor);

            //afiseaza cuvintele

            for (int j = 0; j < nrcuv; j++)

                Console.WriteLine(fraza[j].cuvant);

            //cauta cuvintele pereche in 2 cicluri imbricate

            Console.WriteLine("perechi de cuvinte care rimeaza");

            for(int u=0;u<=nrcuv-1;u++)

            {

                for(int v=u+1;v<nrcuv;v++)

                {

                    bool b1 = fraza[u].folosit;

                    bool b2 = fraza[v].folosit;

                    string s1 = fraza[u].cuvant;

                    string s2 = fraza[v].cuvant;

                    int lg1 = s1.Length;

                    int lg2 = s2.Length;

                    if (lg1>=2&&lg2>=2&&s1[lg1-2]==s2[lg2-2]&&s1[lg1-1]==s2[lg2-1]&&!b1&&!b2)

                    {

                        b1 = true;

                        b2 = true;

                        Console.WriteLine("{0} {1}",fraza[u].cuvant, fraza[v].cuvant);

                    }

                }

            }

            Console.ReadKey();

        }

    }

}