Adds display double circular ll and get middle element of circular double linked list solutions

Author: omonimus1

c++/display-double-circular-linked-list.cpp

@@ -0,0 +1,21 @@
+// https://practice.geeksforgeeks.org/problems/display-circular-doubly-linked-list/1/?track=DSA-Foundation-Final-DLL&batchId=193
+
+void displayList(Node *head)
+{
+    //Head to Tail
+   Node *current = head;
+   while(current->next != head)
+   {
+       cout << current->data << " ";
+       current = current->next;
+   }
+    cout<<current->data<<endl;
+    //Tail to Head
+    while(current != head)
+    {
+        cout << current->data << " ";
+        current = current->prev;
+    }
+    cout <<current->data; 
+    
+}

c++/get_middle_element_of_circular_double_linked-list.cpp

@@ -0,0 +1,32 @@
+// https://practice.geeksforgeeks.org/problems/find-middle-of-circular-doubly-linked-list/1/?track=DSA-Foundation-Final-DLL&batchId=193
+
+// Count number of nodes present in the circular double linked list
+int count_number_of_nodes(Node *head)
+{
+    Node *current_node = head;
+    int counter = 0;
+    while(current_node->next != head)
+    {
+        counter++;
+        current_node = current_node ->next;
+    }
+    return counter;
+}
+
+int findMiddle(Node * head)
+{
+    Node *current = head;
+   int number_nodes = count_number_of_nodes(current);
+   // Get position of the middle element of the linked list
+   int position = (number_nodes/2)+1;
+   
+   current = head;
+   // Iterate until we reach the middle element
+   while(position > 1)
+   {
+       position--;
+       current = current->next;
+   }
+   // Return value of the middle element
+   return current->data;
+}