doubly circular list added

doubly-circular-list.cpp

@@ -0,0 +1,148 @@
+// C++ program to illustrate inserting a Node in
+// a Cicular Doubly Linked list in begging, end
+// and middle
+#include <bits/stdc++.h>
+using namespace std;
+
+// Structure of a Node
+struct Node
+{
+ int data;
+ struct Node *next;
+ struct Node *prev;
+};
+
+// Function to insert at the end
+void insertEnd(struct Node** start, int value)
+{
+ // If the list is empty, create a single node
+ // circular and doubly list
+ if (*start == NULL)
+ {
+ struct Node* new_node = new Node;
+ new_node->data = value;
+ new_node->next = new_node->prev = new_node;
+ *start = new_node;
+ return;
+ }
+
+ // If list is not empty
+
+ /* Find last node */
+ Node *last = (*start)->prev;
+
+ // Create Node dynamically
+ struct Node* new_node = new Node;
+ new_node->data = value;
+
+ // Start is going to be next of new_node
+ new_node->next = *start;
+
+ // Make new node previous of start
+ (*start)->prev = new_node;
+
+ // Make last preivous of new node
+ new_node->prev = last;
+
+ // Make new node next of old last
+ last->next = new_node;
+}
+
+// Function to insert Node at the beginning
+// of the List,
+void insertBegin(struct Node** start, int value)
+{
+ // Pointer points to last Node
+ struct Node *last = (*start)->prev;
+
+ struct Node* new_node = new Node;
+ new_node->data = value; // Inserting the data
+
+ // setting up previous and next of new node
+ new_node->next = *start;
+ new_node->prev = last;
+
+ // Update next and previous pointers of start
+ // and last.
+ last->next = (*start)->prev = new_node;
+
+ // Update start pointer
+ *start = new_node;
+}
+
+// Function to insert node with value as value1.
+// The new node is inserted after the node with
+// with value2
+void insertAfter(struct Node** start, int value1,
+ int value2)
+{
+ struct Node* new_node = new Node;
+ new_node->data = value1; // Inserting the data
+
+ // Find node having value2 and next node of it
+ struct Node *temp = *start;
+ while (temp->data != value2)
+ temp = temp->next;
+ struct Node *next = temp->next;
+
+ // insert new_node between temp and next.
+ temp->next = new_node;
+ new_node->prev = temp;
+ new_node->next = next;
+ next->prev = new_node;
+}
+
+
+void display(struct Node* start)
+{
+ struct Node *temp = start;
+
+ printf("\nTraversal in forward direction \n");
+ while (temp->next != start)
+ {
+ printf("%d ", temp->data);
+ temp = temp->next;
+ }
+ printf("%d ", temp->data);
+
+ printf("\nTraversal in reverse direction \n");
+ Node *last = start->prev;
+ temp = last;
+ while (temp->prev != last)
+ {
+ printf("%d ", temp->data);
+ temp = temp->prev;
+ }
+ printf("%d ", temp->data);
+}
+
+/* Driver program to test above functions*/
+int main()
+{
+ /* Start with the empty list */
+ struct Node* start = NULL;
+
+ // Insert 5. So linked list becomes 5->NULL
+ insertEnd(&start, 5);
+
+ // Insert 4 at the beginning. So linked
+ // list becomes 4->5
+ insertBegin(&start, 4);
+
+ // Insert 7 at the end. So linked list
+ // becomes 4->5->7
+ insertEnd(&start, 7);
+
+ // Insert 8 at the end. So linked list
+ // becomes 4->5->7->8
+ insertEnd(&start, 8);
+
+ // Insert 6, after 5. So linked list
+ // becomes 4->5->6->7->8
+ insertAfter(&start, 6, 5);
+
+ printf("Created circular doubly linked list is: ");
+ display(start);
+
+ return 0;
+}