C++ graph. Program looking for ->()<-

#include <iostream>
using namespace std;

const int n=8;
struct link
{
	char key;
	link *next;
}*g[n];

void init(link *G[n]);
int search_node(link *G[n], char c);
int search_arc(link *G[n], char c1, char c2);
void add_node(link *G[n], char c);
void add_arc(link *G[n], char c1, char c2);
void list_node(link *G[n]){
	cout<<"\n";
	for(int i=0; i<n; i++){
		if(g[i]){
			cout<<g[i]->key;
		}
	}
}
void main()
{
	
	add_node(g, 'A');
	add_node(g, 'B');
	add_node(g, 'C');
	add_node(g, 'D');
	add_node(g, 'E');
	add_node(g, 'F');
	add_node(g, 'G');
	add_node(g, 'H');


	add_arc(g, 'A', 'B');
	add_arc(g, 'A', 'C');
	add_arc(g, 'H', 'C');
	add_arc(g, 'H', 'D');
	add_arc(g, 'B', 'F');
	add_arc(g, 'B', 'H');
	add_arc(g, 'C', 'D');
	add_arc(g, 'D', 'F');
	add_arc(g, 'E', 'G');
	add_arc(g, 'G', 'E');
	
	
	for(int i=0; i<n; i++)
	{
			/*checks for node with two exiting arches and prints the node */
			if(g[i]->next!=NULL && g[i]->next->next!=NULL)	
					cout<<"\nTwo pair of arc from one node: "<<g[i]->key;
	}
	int tra;
	cin>>tra;
}

void init(link *G[n])
{
	for (int i=0; i<n; i++)
		G[i]=NULL;
}

int search_node(link *G[n], char c)
{
	int flag=0;
	for(int i=0; i<n; i++)
	{
		if(G[i])
			if(G[i]->key==c)
			{
				flag=1;
				break;
			}
	}
	return flag;
}

int search_arc(link *G[n], char c1, char c2)
{
	int flag=0;
	if(search_node(G,c1)&&search_node(G,c2))
	{
		int i=0;
		while(G[i]->key!=c1)i++;
		link *p=G[i];
		while(p->key!=c2&&p->next!=NULL)p=p->next;
		if(p->key==c2)flag=1;
	}
	return flag;
}

void add_node(link *G[n], char c)
{
	if(search_node(G,c))
		cout<<"\nNode exists";
	else
	{
		int j=0;
		while(G[j]&&(j<n))j++;
		if(G[j]==NULL)
		{
			G[j]=new link;
			G[j]->key=c;
			G[j]->next=NULL;
		}
		else cout<<"\noverflow occured";
	}
}

void add_arc(link *G[n], char c1, char c2)
{
	int i=0;
	link *p;
	if(search_arc(G,c1,c2))
		cout<<"\nArc exists";
	else
	{
		if(!search_node(G,c1)) {cout<<"DOBB";add_node(G,c1);}
		if(!search_node(G,c2)) {cout<<"DOBB";add_node(G,c2);}
		while(G[i]->key!=c1) i++;
		p=new link;
		p->key=c2;
		p->next=G[i]->next;
		G[i]->next=p;
	}
}