graph

#include<iostream>
using namespace std;
//GRAPH DOMASHNO
const int n=15;
struct link
{
 char key;
 link *next;
}
*gr[n];
void init(link *gr[n]);
int search_node (link*gr[n],char c);
int search_arc(link *gr[n],char c1,char c2);
void add_node (link *gr[n],char c);
void add_arc(link *gr[n],char c1,char c2);
void del_node(link *gr[n],char c);
void del_arc (link *gr[n],char c1,char c2);
void list_node (link *gr[n]);
void main()
{
 char c,k;
 int m;
 do
 {
  cout<<"Menu\n";
  cout<<"1.Init\n";
     cout<<"2.Add node\n";
     cout<<"3.Add arc\n";
  cout<<"4.Del node\n";
  cout<<"5.Del arc\n";
  cout<<"6.Search node\n";
  cout<<"7.Search arc\n";
  cout<<"8.Print All\n";
  cout<<"9.Exit\n";
  cin>>m;
  switch(m)
  {
   case 1:
    init (gr);
    break;
   case 2:
    cout<<"Enter node: ";
     cin>>c;
     add_node(gr,c);
    break;
   case 3:
    cout<<"Enter first node: ";
     cin>>c;
    cout<<"Enter second node: ";
    cin>>k;
    add_arc(gr,c,k);
    break;
   case 4:
    cout<<"Enter node: ";
    cin>>c;
    del_node (gr,c);
    break;
   case 5:
       cout<<"Enter first node: ";
    cin>>c;
    cout<<"Enter second node: ";
    cin>>k;
    del_arc (gr,c,k);
    break;
   case 6:
    cout<<"Enter node: ";
    cin>>k;
    if (search_node (gr,k))
    cout<<"Search result : OK \n";
    else
     cout<<"Search result: NO \n";
    break;
   case 7:
    cout<<"Enter first node: ";
    cin>>c;
    cout<<"Enter second node: ";
    cin>>k;
    if (search_arc(gr,c,k))
     cout<<"Search result : OK\n";
    else
     cout<<"Search result : NO\n";
    break;
   case 8:
    list_node(gr);
  }
 }
 while (m!=9);
 cout<<endl;
 system ("pause");
}
int search_node(link *gr[n],char c)
{
 int flag=0;
 for (int i=0;i<n;i++)
  if (gr[i])
   if(gr[i]->key==c)
    flag=1;
 return flag;
}
int search_arc(link *gr[n],char c1,char c2)
{
 int flag=0;
 if (search_node(gr,c1) && search_node(gr,c2))
 {
  int i=0;
  while (gr[i]->key!=c1)
   i++;
  link *p=gr[i];
  while(p->key!=c2 && p->next !=NULL)
   p=p->next;
  if(p->key==c2)
   flag=1;
 }
return flag;
}
void add_node (link *gr[n],char c)
{
 if (search_node(gr,c))
  cout<<"\n Existing node \n";
 else
 {
  int j=0;
  while (gr[j] && j<n)
   j++;
  if (gr[j]==NULL)
  {
   gr[j]=new link;
   gr[j]->key=c;
   gr[j]->next=NULL;
  }
  else
   cout<<"\n Overflow \n";
 }
}
void add_arc(link *gr[n],char c1,char c2)
{
 if (search_arc(gr,c1,c2))
  cout<<"\n Existing arc \n";
 else
 {
  if(!search_node(gr,c1))
   add_node(gr,c1);
  if (!search_node(gr,c2))
   add_node (gr,c2);
   int i=0;
  link *p;
  while (gr[i]->key!=c1)
   i++;
  p=new link;p->key=c2;
  p->next=gr[i]->next;gr[i]->next=p;
 }
}
  void list_node(link *gr[n])
  {
   for (int i=0;i<n;i++)
    if (gr[i])
     cout<<gr[i]->key;
   cout<<endl;
  }
  void init (link *gr[n])
  {
   for (int i=0;i<n;i++)
    gr[i]=NULL;
  }
  void del_node(link *gr[n],char c)
  {
   if (search_node (gr,c))
   {
   int i=0; link *p=NULL, *q=NULL;
   while (gr[i]->key!=c)
    i++;
   while (gr[i] !=NULL)
   {
    p=gr[i];
    gr[i]=gr[i]->next;
    delete p;
   }
   for (i=0;i<n;i++)
    if (gr[i])
    {
     p=gr[i];
     while (p->key!=c && p->next!=NULL)
     {
      q=p;
      p=p->next;
     }
     if (p->key==c)
     {
      q->next=p->next;
      delete p;
     }
    }
   }
   else
    cout<<"The mode is not in the graph";
   cout<<endl;
   }
    void del_arc(link *gr[n],char c1,char c2)
    {
     int i=0; link *p=NULL, *q=NULL;
     if (search_arc (gr,c1,c2))
     {
      while (gr[i]->key!=c1)
       i++;
      p=gr[i];
      while (p->key!=c2)
      {
       q=p;p=p->next;
      }
      q->next=p->next;
      delete p;
     }
     else
      cout<<"The arc is not in the graph" ;
     cout<<endl;
    }