From fc7e680dab81b8d53b9a0eca931600d927bccc57 Mon Sep 17 00:00:00 2001
From: BumbleBee <shubhammaurya20121998@gmail.comm>
Date: Tue, 15 Oct 2019 19:36:44 +0530
Subject: [PATCH] doubly circular list added

---
 doubly-circular-list.cpp | 148 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 doubly-circular-list.cpp

diff --git a/doubly-circular-list.cpp b/doubly-circular-list.cpp
new file mode 100644
index 0000000..3d66a21
--- /dev/null
+++ b/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;
+}