Added a new type of Linked list named Circular linked list

C - C++/Circular Linked List/Readme.md

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+Circular singly linked list is a type of data structure that is made up of nodes that are created using self referential structures. Each of these nodes contain two parts, namely the data and the reference to the next list node.
+
+Only the reference to the first list node is required to access the whole linked list. This is known as the head. The last node in the list points to head or first node of the list. That is the reason this is known as a circular linked list.
+
+# Problem Statement:- 
+All operations like insertion, deletion and traversal by using a circular linkedlist
+
+# output:-
+The circular linked list created is as follows:
+
+10==>20==>30==>40==>50==>60==>10
+
+The node with data 10 is deleted from the list
+
+Circular linked list after deleting 10 is as follows:
+
+20==>30==>40==>50==>60==>20
+
+##### Contributed By 
+[Subrata Bhuin](https://github.com/Over-Thinker)

C - C++/Circular Linked List/circluar.cpp

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+#include<iostream>
+using namespace std;
+
+struct Node
+{
+   int data;
+   struct Node *next;
+};
+//insert a new node in an empty list
+struct Node *insertInEmpty(struct Node *last, int new_data)
+{
+   // if last is not null then list is not empty, so return
+   if (last != NULL)
+   return last;
+
+   // allocate memory for node
+   struct Node *temp = new Node;
+
+   // Assign the data.
+   temp -> data = new_data;
+   last = temp;
+
+   // Create the link.
+   last->next = last;
+
+   return last;
+}
+//insert new node at the beginning of the list
+struct Node *insertAtBegin(struct Node *last, int new_data)
+{
+   //if list is empty then add the node by calling insertInEmpty
+   if (last == NULL)
+   return insertInEmpty(last, new_data);
+
+   //else create a new node
+   struct Node *temp = new Node;
+
+   //set new data to node
+   temp -> data = new_data;
+   temp -> next = last -> next;
+   last -> next = temp;
+
+   return last;
+}
+//insert new node at the end of the list
+struct Node *insertAtEnd(struct Node *last, int new_data)
+{
+   //if list is empty then add the node by calling insertInEmpty
+   if (last == NULL)
+   return insertInEmpty(last, new_data);
+
+   //else create a new node
+   struct Node *temp = new Node;
+
+   //assign data to new node
+   temp -> data = new_data;
+   temp -> next = last -> next;
+   last -> next = temp;
+   last = temp;
+
+   return last;
+}
+
+//insert a new node in between the nodes
+struct Node *insertAfter(struct Node *last, int new_data, int after_item)
+{
+   //return null if list is empty
+   if (last == NULL)
+   return NULL;
+
+   struct Node *temp, *p;
+   p = last -> next;
+   do
+   {
+      if (p ->data == after_item)
+      {
+         temp = new Node;
+         temp -> data = new_data;
+         temp -> next = p -> next;
+         p -> next = temp;
+
+         if (p == last)
+         last = temp;
+         return last;
+       }
+   p = p -> next;
+ } while(p != last -> next);
+
+   cout << "The node with data "<<after_item << " is not present in the list." << endl;
+   return last;
+
+}
+//traverse the circular linked list
+void traverseList(struct Node *last) {
+   struct Node *p;
+
+   // If list is empty, return.
+   if (last == NULL) {
+      cout << "Circular linked List is empty." << endl;
+      return;
+      }
+p = last -> next; // Point to the first Node in the list.
+
+// Traverse the list starting from first node until first node is visited again
+
+do {
+      cout << p -> data << "==>";
+      p = p -> next;
+      } while(p != last->next);
+   if(p == last->next)
+   cout<<p->data;
+   cout<<"\n\n";
+   }
+
+//delete the node from the list
+void deleteNode(Node** head, int key)
+{
+   // If linked list is empty retun
+   if (*head == NULL)
+   return;
+
+   // If the list contains only a single node,delete that node; list is empty
+   if((*head)->data==key && (*head)->next==*head) {
+      free(*head);
+      *head=NULL;
+      }
+Node *last=*head,*d;
+
+// If key is the head
+if((*head)->data==key) {
+   while(last->next!=*head) // Find the last node of the list
+   last=last->next;
+
+   // point last node to next of head or second node of the list
+   last->next=(*head)->next;
+   free(*head);
+   *head=last->next;
+   }
+
+// end of list is reached or node to be deleted not there in the list
+while(last->next!=*head&&last->next->data!=key) {
+   last=last->next;
+}
+// node to be deleted is found, so free the memory and display the list
+if(last->next->data==key) {
+      d=last->next;
+      last->next=d->next;
+      cout<<"The node with data "<<key<<" deleted from the list"<<endl;
+      free(d);
+      cout<<endl;
+      cout<<"Circular linked list after deleting "<<key<<" is as follows:"<<endl;
+      traverseList(last);
+      }
+   else
+   cout<<"The node with data "<< key << " not found in the list"<<endl;
+   }
+
+// main Program
+int main()
+{
+   struct Node *last = NULL;
+
+   last = insertInEmpty(last, 30);
+   last = insertAtBegin(last, 20);
+   last = insertAtBegin(last, 10);
+   last = insertAtEnd(last, 40);
+   last = insertAtEnd(last, 60);
+   last = insertAfter(last, 50,40 );
+   cout<<"The circular linked list created is as follows:"<<endl;
+   traverseList(last);
+   deleteNode(&last,10);
+   return 0;
+}