Merge pull request bhrigukansra#83 from priyankamadhwal/patch-1

Implemented Circular Linked List.

Author: Bhrigu Kansra

Data Structures/CircularLinkedList.cpp

@@ -0,0 +1,276 @@
+//Implementation of Circular Linked List
+
+#include<iostream>
+using namespace std;
+
+template<class T>
+struct NODE
+{
+	T info;				//Information in the node.
+	NODE<T> *next;			//Points to the next node.
+};
+
+typedef NODE<char>* NPTR;
+
+template<class T>
+class CLL
+{
+	NPTR Head;			//Points to the first node.
+	public:
+		CLL()			//Constructor
+		{
+			Head=NULL;
+		}
+		~CLL()			//Destructor
+		{
+			delete Head;
+		}
+		NPTR GetNode();						//To get a new node.
+		NPTR SearchNode(T);					//To search a node in the linked list.
+		void Create(T);						//To create a new linked list.
+		void InsertBefore(T, T);			//To insert a new node BEFORE the given node in the linked list.
+		void InsertAfter(T, T);				//To insert a new node AFTER the given node in the linked list.
+		void DeleteNode(T);					//To delete a node in the linked list.
+		void UpdateNode(T, T);				//To update a node of the linked list.
+		int Size();							//Returns the size of linked list.
+		void Traverse();					//To display the linked list.
+		void Reverse();						//To reverse the linked list.
+};
+
+template<class T>
+NPTR CLL<T>::GetNode()
+{
+	return new NODE<T>;
+}
+
+template<class T>
+NPTR CLL<T>::SearchNode(T elt)
+{
+	NPTR P=Head;
+	if (P!=NULL)
+	{
+		while (P->next!=Head && P->info!=elt)
+			P=P->next;
+		if (P->info==elt)
+			return P;
+	}
+	return NULL;
+}
+
+template<class T>
+void CLL<T>::Create(T elt)
+{
+	NPTR P=GetNode();
+	P->info=elt;
+	P->next=P;
+	Head=P;
+	cout<<"\nLinked list successfully created!!!"<<endl<<endl;
+}
+
+template<class T>
+void CLL<T>::InsertBefore(T new_elt, T before_elt)
+{
+	NPTR P=SearchNode(before_elt);
+	if (P==NULL)
+	{
+		cout<<"\nERROR!!!\nNode before which you want to insert the new node is not found."<<endl<<endl;
+	}
+	else
+	{
+		NPTR Q=GetNode();
+		Q->info=new_elt;
+		Q->next=P;
+		NPTR R=Head;
+		while (R->next!=P)
+			R=R->next;
+		R->next=Q;
+		if (P==Head)
+			Head=Q;
+		cout<<"\nSUCCESS!!!\nNew node is successfully inserted before the given node."<<endl<<endl;		
+	}
+}
+
+template<class T>
+void CLL<T>::InsertAfter(T new_elt, T after_elt)
+{
+	NPTR P=SearchNode(after_elt);
+	if (P==NULL)
+	{
+		cout<<"\nERROR!!!\nNode after which you want to insert the new node is not found."<<endl<<endl;
+	}
+	else
+	{
+		NPTR Q=GetNode();
+		Q->info=new_elt;
+		Q->next=P->next;
+		P->next=Q;
+		cout<<"\nSUCCESS!!!\nNew node is successfully inserted after the given node."<<endl<<endl;
+	}
+}
+
+template<class T>
+void CLL<T>::DeleteNode(T elt)
+{
+	NPTR P=SearchNode(elt);
+	if (P==NULL)
+	{
+		cout<<"\nERROR!!!\nNode that you want to delete is not found!"<<endl<<endl;
+	}
+	else
+	{
+		if (P->next==P)			//If there is only one node (i.e. P=Head).
+		{
+			Head=NULL;
+		}
+		else
+		{
+			if (P==Head)
+				Head=Head->next;
+			NPTR Q=Head;
+			while (Q->next!=P)
+				Q=Q->next;
+			Q->next=P->next;
+
+		}
+		delete P;
+		cout<<"\nSUCCESS!!!\nThe node is successfully deleted."<<endl<<endl;
+	}
+}
+
+template<class T>
+void CLL<T>::UpdateNode(T prev_elt, T new_elt)
+{
+	NPTR P=SearchNode(prev_elt);
+	if (P==NULL)
+	{
+		cout<<"\nERROR!!!\nNode that you want to update is not found."<<endl<<endl;
+	}
+	else
+	{
+		P->info=new_elt;
+		cout<<"\nSUCCESS!!!\nNode is successfully updated."<<endl<<endl;
+	}
+}
+
+template<class T>
+int CLL<T>::Size()
+{
+	int count=0;
+	if (Head!=NULL)
+	{
+		for (NPTR P=Head; P->next!=Head; P=P->next, count++);
+		++count;
+	}
+	return count;
+}
+
+template<class T>
+void CLL<T>::Traverse()
+{
+	if (Head==NULL)
+	{
+		cout<<"\nThe Linked list is empty.";
+	}
+	else
+	{
+		NPTR P=Head;
+		
+		do
+		{
+			cout<<" --> "<<P->info;
+			P=P->next;
+		}
+		while(P!=Head);
+		cout<<" --> ";
+	}
+	cout<<endl<<endl;
+}
+
+template<class T>
+void CLL<T>::Reverse()
+{
+	if (Head==NULL)
+		cout<<"\nThe Linked list is empty.";
+	else
+	{
+		NPTR P=NULL;
+		NPTR Q;
+		NPTR R=Head;
+		while (Head->next!=R)
+		{
+			NPTR Q=Head->next;
+			Head->next=P;
+			P=Head;
+			Head=Q;
+		}
+		Head->next=P;
+		R->next=Head;
+		cout<<"\nSUCCESS!!! The linked list is successfully reversed.";
+	}
+	cout<<endl<<endl;
+}
+
+int main()
+{
+	cout<<"********************************** CIRCULAR LINKED LIST ********************************** ";
+	CLL<char> CL_list;
+	char choice;
+	int flag=1;
+	char element1, element2;
+	while(flag)
+	{
+		cout<<"\n1. Create";
+		cout<<"\n2. Traverse";
+		cout<<"\n3. Insert Before";
+		cout<<"\n4. Insert After";
+		cout<<"\n5. Delete Node";
+		cout<<"\n6. Update Node";
+		cout<<"\n7. Size";
+		cout<<"\n8. Reverse";
+		cout<<"\n9. Exit";
+		cout<<"\n\nEnter choice : ";
+		cin>>choice;
+		switch(choice)
+		{
+			case '1'	:	cout<<"\nEnter first node : ";
+							cin>>element1;
+							CL_list.Create(element1);
+							break;
+			case '2'	:	cout<<endl;
+							CL_list.Traverse();
+							break;
+			case '3'	:	cout<<"\nEnter the node you want to insert : ";
+							cin>>element1;
+							cout<<"\nEnter the node before which you want to insert your node : ";
+							cin>>element2;
+							CL_list.InsertBefore(element1,element2);
+							break;
+			case '4'	:	cout<<"\nEnter the node you want to insert : ";
+							cin>>element1;
+							cout<<"\nEnter the node after which you want to insert your node : ";
+							cin>>element2;
+							CL_list.InsertAfter(element1,element2);
+							break;
+			case '5'	:	cout<<"\nEnter the node that you want to delete : ";
+							cin>>element1;
+							CL_list.DeleteNode(element1);
+							break;
+			case '6'	:	cout<<"\nEnter the node you want to update : ";
+							cin>>element1;
+							cout<<"\nEnter the new node : ";
+							cin>>element2;
+							CL_list.UpdateNode(element1,element2);
+							break;
+			case '7'	:	cout<<"\nThe size of the linked list is : "<<CL_list.Size()<<endl<<endl;
+							break;
+			case '8'	:	CL_list.Reverse();
+							break;
+			case '9'	:	flag=0;
+							break;
+			default		:	cout<<"\n\nERROR!!! You entered a wrong choice."<<endl<<endl;
+		}
+	}
+	cout<<endl;
+	system("pause");
+	return 0;
+}