Adjacency Lists + DFS.

// Adjacency Lists + DFS.#ifndef _IOSTREAM_H#include <iostream.h>#include <conio.h>#define _IOSTREAM_H#endifenum Boolean { FALSE, TRUE};template <class Type> class List;template <class Type> class ListIterator;template <class Type>class ListNode {friend class List<Type>;friend class ListIterator<Type>;private:   Type data;   ListNode *link;   ListNode(Type);};template <class Type>ListNode<Type>::ListNode(Type Default){   data = Default;   link = 0;}template <class Type>class List {friend class ListIterator<Type>;public:    List() {first = 0;};    void Insert(Type);    void Delete(Type);private:    ListNode<Type> *first;};template <class Type>void List<Type>::Insert(Type k){ListNode<Type> *newnode = new ListNode<Type>(k);newnode->link = first;first = newnode;}template <class Type>void List<Type>::Delete(Type k){   ListNode<Type> *previous = 0;   ListNode<Type> *current;for (current = first; current && current->data != k;previous = current, current = current->link);   if (current)   {       if (previous)       previous->link = current->link;       else       first = first->link;       delete current;   }}template <class Type>class ListIterator{public:    ListIterator(const List<Type>& l): list(l) {current = l.first;}    Type* First();    Type* Next();    Boolean NotNull();    Boolean NextNotNull();private:    const List<Type> &list;    ListNode<Type>* current;};template <class Type>Type* ListIterator<Type>::First() {      if (current) return &current->data;      else return 0;}template <class Type>Type* ListIterator<Type>::Next() {      current = current->link;      return &current->data;}template <class Type>Boolean ListIterator<Type>::NotNull(){if (current) return TRUE;else return FALSE;}template <class Type>Boolean ListIterator<Type>::NextNotNull(){if (current->link) return TRUE;else return FALSE;}//template <class Type>ostream& operator<<(ostream& os, List<char>& l){    ListIterator<char> li(l);    if (!li.NotNull()) return os;    os << *li.First() << endl;    while  (li.NextNotNull()) os << *li.Next() << endl;    return os;}class Graph{private:    List<int> *HeadNodes;    int n;    void DFS(const int);    Boolean *visited;    int num;    int *low;    int *dfn;    void DfnLow(const int, const int);public:    Graph(const int vertices = 0) : n(vertices)    { HeadNodes = new List<int>[n];};    void DFS();    void Setup();    void Setup2();    void DfnLow(const int);    void Components();    void Out();};void Graph::Setup(){   HeadNodes[0].Insert(2); HeadNodes[0].Insert(1);   HeadNodes[1].Insert(4); HeadNodes[1].Insert(3); HeadNodes[1].Insert(0);   HeadNodes[2].Insert(6); HeadNodes[2].Insert(5); HeadNodes[2].Insert(0);   HeadNodes[3].Insert(7); HeadNodes[3].Insert(1);   HeadNodes[4].Insert(7); HeadNodes[4].Insert(1);   HeadNodes[5].Insert(7); HeadNodes[5].Insert(2);   HeadNodes[6].Insert(7); HeadNodes[6].Insert(2);   HeadNodes[7].Insert(6); HeadNodes[7].Insert(5); HeadNodes[7].Insert(4);   HeadNodes[7].Insert(3);}void Graph::Setup2(){   HeadNodes[0].Insert(1);                                                 //   HeadNodes[1].Insert(2); HeadNodes[1].Insert(3); HeadNodes[1].Insert(0);//   HeadNodes[2].Insert(1); HeadNodes[2].Insert(4); //   HeadNodes[3].Insert(5); HeadNodes[3].Insert(1); HeadNodes[3].Insert(4);//   HeadNodes[4].Insert(3); HeadNodes[4].Insert(2); //   HeadNodes[5].Insert(7); HeadNodes[5].Insert(6);//   HeadNodes[6].Insert(7); HeadNodes[6].Insert(5);//   HeadNodes[7].Insert(6); HeadNodes[7].Insert(5); HeadNodes[7].Insert(8);   HeadNodes[7].Insert(9);   HeadNodes[8].Insert(7);   HeadNodes[9].Insert(7);}// Drivervoid Graph::DFS(){    visited = new Boolean[n]; // @visited@ is declared as a @Boolean@/(** data member of @Graph@.    for (int i = 0; i < n; i++)    visited[i] = FALSE; // initially, no vertices have been visited    DFS(0); // start search at vertex 0    delete [] visited;}// Workhorsevoid Graph::DFS(const int v)//  visit all previously unvisited vertices that are reachable from vertex @v@{visited[v] = TRUE;  cout << v << ", ";   ListIterator<int> li(HeadNodes[v]);   if (! li.NotNull())   return;   int w = *li.First();   while (1)   {   if (! visited[w])      DFS(w);      if (li.NextNotNull())      w = *li.Next();      else      return;   }}void Graph::Components(){int i;   visited = new Boolean[n];   for (i = 0; i < n; i++)   visited[i] = FALSE;   for (i = 0; i < n; i++)   if (! visited[i])   {cout << endl << "New Component :";   DFS(i); // @DFS@ is modified to print a vertex when it is visited}   delete [] visited;}void Graph::DfnLow(const int x){   num = 1;   dfn = new int[n];   low = new int[n];   for (int i = 0; i < n; i++) { dfn[i] = low[i] = 0;}   DfnLow(x, -1);   delete [] dfn;   delete [] low;}void Graph::DfnLow (const int u, const int v){dfn[u] = low[u] = num++;   ListIterator<int> li(HeadNodes[u]);   if (! li.NotNull())   return;int w = *li.First();   while (1)   {if (dfn[w] == 0)      {    DfnLow(w, u);    if (low[w] < low[u])         low[u] = low[w];}else      {   if (w != v)         {         if (dfn[w] < low[u])            low[u] = dfn[w];         }}if (li.NextNotNull())      w = *li.Next();else      return;   }}void Graph::Out(){for (int i = 0; i < n; i++)   {   cout << i << ": " << dfn[i] << "    " << low[i] << endl;}}void main(){ Graph g(10); g.Setup2();// g.Components(); g.DfnLow(3); g.Out(); getch();}