#include

#include

using namespace std;

// what is Color_Size and why it is at the end?

enum Color

{

       Red, Yellow, Green, Color_Size

};

// what is Node *next and why it is there?

struct Node

{

       Color color;

       Node *next;

};

// explain the code below

void addNode(Node* &first, Node* &last, const Color &c)

{

       if (first == NULL)

       {

              first = new Node;

              first->color = c;

              first->next = NULL;

              last = first;

       }

       else

       {

              last->next = new Node;

              last->next->color = c;

              last->next->next = NULL;

              last = last->next;

       }

}

// explain the code below

string colorToString(const Color &c)

{

       if (c == Red) return "Red";

       else if (c == Yellow) return "Yellow";

       else if (c == Green) return "Green";

}

// explain the code below

Color intToColor(const int &i)

{

       if (i == 0) return Red;

       else if (i == 1) return Yellow;

       else if (i == 2) return Green;

       else return Color_Size;

}

// explain the code below and why the number 48 is there?

Color charToColor(const char &c)

{

       if (c >= 48 && c <= (48 + Color_Size - 1))

       {

              return intToColor(c - 48);

       }

       else

       {

              return Color_Size;

       }

}

// explain the code below

string printNodes(Node* &first)

{

       if (first == NULL) return "";

       Node *n = first;

       string text = "List: ";

       while (n != NULL)

       {

              if (n->color == Red) text += colorToString(Red);

              else if (n->color == Yellow) text += colorToString(Yellow);

              else if (n->color == Green) text += colorToString(Green);

              if (n->next != NULL) text += ", ";

              n = n->next;

       }

       return text;

}

// explain the code below

string printMenu()

{

       string text = "Choose Color to Add to the List:\n";

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

       {

              text += to_string(i) + "> ";

              text += colorToString(intToColor(i));

              text += "\n";

       }

       text += to_string(Color_Size) + "> " + "Print List";

       return text;

}

// explain the code below

bool invalidInput(const char &input)

{

       return (input < 48) || (input > (48 + Color_Size));

}

// explain the code below

void freeMemory(Node* &first)

{

       if (first == NULL) return;

       Node *n = first;

       while (n != NULL)

       {

              first = first->next;

              delete n;

              n = first;

       }

}

int main()

{

       bool loopIt = true;

       char input;

       Node *first, *last;

       first = NULL;

       last = NULL;

       while (loopIt)

       {

              cout << printMenu() << endl << endl;

              cout << "Input: ";

              cin >> input;

              cout << endl;

              if (invalidInput(input))

              {

                     cout << "invalid input! the app will close . . ." << endl;

                     loopIt = false;

              }

              else

              {

                     if (charToColor(input) == Color_Size)

                     {

                           cout << printNodes(first) << endl << endl;

                     }

                     else

                     {

                           addNode(first, last, charToColor(input));

                     }

              }

       }

       freeMemory(first);

       system("pause");

       return 0;

}