Question

C++ preffered please, thank you.

Write a code in a high-level language (C++, C# or Java or ??) for a Deterministic Pushdown automaton which will accept the string a^nb^n where sigma = a, b. Create an input file with the following strings aaabbb, ababab, aababb, abbaab and give your output showing what is accepted and what is not accepted.

Answer 1

Answer:

#include <iostream>

#include <cstdlib>

#include <fstream>

#include <list>

#include <vector>

#include <map>

#include <sstream>

class PDA1

{

            public:

                        PDA1(string filename);

                        PDA1 ();

                        void isAccepted(string str);

            private:

                        void populateTransitionTable1(ifstream *p);

                        void initialOuput1(string s);

                        void output1(string s, string k, unsigned int i);

                        string showCurrentStack1();

                        void notAccepted1(string str);

                        int numStates1;

                        string endStates1;

                        string alphabet1;

                        list <string> s;

                        map<string, string> m;

                        map<string, int> moveNum1;

                        string currentState1;

};

int main ()

{

           

            ifstream inStream1;

            inStream1.open("grammer.txt");

            int nDPDA1;

            inStream1 >> nDPDA1;

            list<PDA1> generic1;

            for (int i = 0; i < nDPDA1; i++)

            {

                        string temp;

                        inStream1 >> temp;

                        generic1.push_back(PDA1(temp));

            }

           

            inStream1.close();

            return 0;

}

PDA1::PDA1(string filename1)

{

            ifstream file1;

            file1.open(filename1.c_str());

            if (file1.fail())

            {

                        cout << "Trouble Opening File\n";

                        exit(1);

            }

           

            file1 >> numStates1;

            file1 >> endStates1;

           

           

            file1 >> alphabet1;

           

            ifstream *pointer = &file1;

            populateTransitionTable1 (pointer);

            currentState1 = "0";

            s.push_back("Z0");

           

           

            char buff[256];

            file1.getline(buff, 256);

            string temp(buff);       

            while (! file1.eof())

            {

                        isAccepted(temp);

                        file1 >> temp;

            }

            file1.close();

}

void PDA1::populateTransitionTable1 (ifstream *p1)

{

            int n;

            *p1 >> n;

            string temp1;

            string key1= "";

            string value1 = "";

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

            {

                       

                        for (int i = 0; i < 3; i++)

                        {

                                    *p1 >> temp1;

                                    key.append (temp1);

                        }

                        for (int i = 0; i < 2; i++)

                        {

                                    *p1 >> temp1;

                                    value1.append(temp1);

                        }

                        moveNum1.insert(pair<string, int>(key, k+1));

                        m.insert(pair<string, string>(key, value1));

                        key = "";

                        value1 = "";

            }

}

void PDA1::isAccepted(string str1)

{

           

            string c = str.substr(0);

            str.append("#");

            alphabet1.append("#");

            string temp1Key = "";

            string operation = "";

            initialOuput1(c);

            for (unsigned int i = 0; i < str.size(); i++)

            {

                       

                        unsigned int alpha = alphabet1.find((str.c_str())[i]);

                        if (alpha == string::npos)

                        {

                                    cout<<"(Crash)\n";

                                    break;

                        }

                       

                        temp1Key.append("(");

                        temp1Key.append(currentState);

                        temp1Key += (str.c_str())[i];

                        temp1Key.append(s.back());

                        temp1Key.append(")");

                       

                       

                        map<string, string>::iterator it = m.find(temp1Key);

                       

                        if (it != m.end())

                        {

                        stringstream out;

                        out << m.find(temp1Key)->second;

                        operation = out.str();

                        out.str("");

                        }

                        else

                        {         

                                    break;

                        }

                       

                        currentState1 = operation.c_str()[1];

                       

                       

                       

                        string decision = operation.substr(2);

                        unsigned int found = decision.find("^", 0);

                        if (found != string::npos)

                        {

                                    s.pop_back();

                        }

                        else

                        {

                                    string nextFind = "";

                                    nextFind+=(str.c_str())[i];

                                    nextFind+="Z0";

                                    found = decision.find(nextFind, 0);

                                    if (found != string::npos)

                                    {

                                                nextFind=str.c_str()[i];

                                                s.push_back(nextFind);

                                    }

                                    else

                                    {

                                                nextFind="";

                                                nextFind+=(str.c_str())[i];

                                                found = decision.find(nextFind, 0);

                                                if (found != string::npos)

                                                {

                                                            s.push_back(nextFind);

                                                }

                                    }

                        }

                        output1(c, temp1Key, i+1);

                       

                        temp1Key = "";

                        operation = "";

            }

            unsigned int isEnd = endStates1.find(currentState1,0);

            if (isEnd != string::npos)

            {

                        cout << "(Accepted)\n\n\n";

            }

            else

            {

                        cout << "(Not Accepted)\n\n\n";

            }

           

           

            currentState1 = "0";

            s.clear();

            s.push_back("Z0");

}

void PDA1::initialOuput1 (string c)

{

            cout << "(initially)\t"<<currentState<<"\t\t"<<c;

           

            if (c.size() < 8) cout<<"\t\t";

            else cout<< "\t";

           

            cout<<showCurrentStack1()<<"\n\n";

}

void PDA1::output1 (string c, string key,unsigned int iteration)

{

                        cout<< moveNum1.find(key)->second << "\t\t" << currentState1

                                    << "\t\t";

                        if (c.size() > iteration)

                        {

                                    cout << c.substr(iteration);

                                    if ((c.substr(iteration)).size() < 8)

                                                cout << "\t\t";

                                    else

                                                cout << "\t";

                        }

                        else { cout << "\t\t"; }

                        cout << showCurrentStack1() <<"\n";

}

string PDA1::showCurrentStack1 ()

{

            string stackState = "";

            list<string> temp1 (s);

            while (temp1.size() > 0)

            {

                        stackState.append(temp1.back());

                        temp1.pop_back();

            }

            return stackState;

}