depth first search c++ - c++

Question

Hello i am working on this project on depth first search, the program uses a linkedlist for each adjacent vertex and use a stack. The program has two structures a Vertex Struct that has two fields a linkedlist pointer and a boolean variable called visted marked as false. The second struct is a Graph that has two fields an array of Vertex Struct and an integer for the number of vertices. The problem i have if when the depth first search function is called it never stops even if the stack is empty the depth first function prints each vertices that is visited. Can someone help me with finding a way to make the program stop ones the stack is empty;
#include <iostream>
#include "linklist.h"
#include "Stack.h"
using namespace std;
typedef int vertexNum;
Stack S;
struct Vertex
{
List p;
bool visted;
Vertex()
{
p = NULL;
visted = false;
}
};
struct Graph
{
int numVert;
Vertex* vertArr;
Graph(int num)
{
numVert = num;
vertArr = new Vertex[numVert+1];
}
};
void readGraph(Graph& G)
{
cout << "Enter adjacent vertices, enter 0 to stop" << endl;
vertexNum v1, v2;
cin >> v1;
while (v1 != 0)
{
cin >> v2;
insertTail(v2,G.vertArr[v1].p);
insertTail(v1,G.vertArr[v2].p);
//G.vertArr[v1].p = cons(v2,G.vertArr[v1].p);
//G.vertArr[v2].p = cons(v1,G.vertArr[v2].p);
cin >> v1;
}
}
void printGraph(Graph& G)
{
for (int i = 1; i <= G.numVert; i++)
{
cout << "Vertex "<< i << " Adjacent list ";
printList(G.vertArr[i].p);
}
}
void DFS(int x,Graph& G)
{
push(x,S);
printList(S.p);
G.vertArr[x].visted = true;
if (!G.vertArr[head(G.vertArr[x].p)].visted)
{
DFS(head(G.vertArr[x].p),G);
}
else
{
cout << ""<< endl;
List temp = tail(G.vertArr[x].p);
if(isEmpty(temp))
{
pop(S);
G.vertArr[peek(S)].visted = false;
DFS(pop(S),G);
}
else if(!G.vertArr[head(temp)].visted)
{
DFS(head(temp),G);
}
else
{
int num =0;
for (List pp = temp; !isEmpty(pp); pp = tail(pp))
{
if(!G.vertArr[head(pp)].visted)
{
num = head(pp);
break;
}
}
if (num == 0)
{
pop(S);
G.vertArr[peek(S)].visted = false;
DFS(pop(S),G);
}
else
DFS(num,G);
}
}
}
int main()
{
int x,y;
cout << "Enter the number of vertices" << endl;
cin >> x;
Graph p(x);
readGraph(p);
printGraph(p);
cout << "\nEnter start vertex" << endl;
cin >> y;
DFS(y,p);
}
The program outputs
Enter the number of vertices
13
Enter adjacent vertices, enter 0 to stop
1 4
1 5
1 2
1 3
2 7
2 8
8 13
8 7
11 12
10 9
13 12
9 6
6 5
0
Vertex 1 Adjacent list 4 5 2 3
Vertex 2 Adjacent list 1 7 8
Vertex 3 Adjacent list 1
Vertex 4 Adjacent list 1
Vertex 5 Adjacent list 1 6
Vertex 6 Adjacent list 9 5
Vertex 7 Adjacent list 2 8
Vertex 8 Adjacent list 2 13 7
Vertex 9 Adjacent list 10 6
Vertex 10 Adjacent list 9
Vertex 11 Adjacent list 12
Vertex 12 Adjacent list 11 13
Vertex 13 Adjacent list 8 12
Enter start vertex
5
5
1 5
4 1 5
1 5
2 1 5
7 2 1 5
8 7 2 1 5
13 8 7 2 1 5
12 13 8 7 2 1 5
11 12 13 8 7 2 1 5
12 13 8 7 2 1 5
13 8 7 2 1 5
8 7 2 1 5
7 2 1 5
2 1 5
1 5
3 1 5
1 5
5
6 5
9 6 5
10 9 6 5
9 6 5
6 5
5
Here is the stack and linkedlist h files
#ifndef LINKLIST_H_
#define LINKLIST_H_
#include <cstdlib>
#include <iostream>
using namespace std;
struct listCell
{
int head;
listCell* tail;
listCell(int h, listCell* t)
{
head =h;
tail = t;
}
};
typedef listCell* List;
typedef const listCell* constList;
List emptyList = NULL;
int head(List L)
{
return L->head;
}
List tail(List L)
{
return L->tail;
}
bool isEmpty(List L)
{
return L == emptyList;
}
List cons(int h, List t)
{
return new listCell(h,t);
}
int listLength(List L)
{
if (isEmpty(L))
{
return 0;
}
else
{
return 1 + listLength(tail(L));
}
}
void printList(List L)
{
List k = L;
while (!isEmpty(k))
{
int val = head(k);
k = k->tail;
cout << val << " ";
}
cout << "\n";
}
here is the stack file
#ifndef STACK_H_
#define STACK_H_
#include "linklist.h"
struct Stack
{
List p;
Stack()
{
p = NULL;
}
};
void push(int x, Stack& list)
{
list.p =cons(x,list.p);
}
int peek(Stack& list)
{
return head(list.p);
}
int pop(Stack& list)
{
return delHead(list.p);
}
bool isEmpty(Stack& list)
{
return isEmpty(list.p);
}
int size(Stack& list)
{
return listLength(list.p);
}
#endif /* STACK_H_ */