From 76fa944622599193241c3494a6c6c4cd7bfd8148 Mon Sep 17 00:00:00 2001
From: pjain312 <53072822+pjain312@users.noreply.github.com>
Date: Mon, 14 Oct 2019 15:19:17 +0530
Subject: [PATCH] Create doublyLL.cpp

---
 doublyLL.cpp | 107 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 107 insertions(+)
 create mode 100644 doublyLL.cpp

diff --git a/doublyLL.cpp b/doublyLL.cpp
new file mode 100644
index 0000000..979c5ab
--- /dev/null
+++ b/doublyLL.cpp
@@ -0,0 +1,107 @@
+#include <bits/stdc++.h> 
+using namespace std; 
+
+class Node 
+{ 
+	public: 
+	int data; 
+	Node* next; 
+	Node* prev; 
+}; 
+
+void push(Node** head_ref, int new_data) 
+{ 
+	Node* new_node = new Node(); 
+	new_node->data = new_data; 
+
+	new_node->next = (*head_ref); 
+	new_node->prev = NULL; 
+	if ((*head_ref) != NULL) 
+		(*head_ref)->prev = new_node; 
+
+	(*head_ref) = new_node; 
+} 
+
+void insertAfter(Node* prev_node, int new_data) 
+{ 
+	if (prev_node == NULL) 
+	{ 
+		cout<<"the given previous node cannot be NULL"; 
+		return; 
+	} 
+
+	Node* new_node = new Node(); 
+
+	new_node->data = new_data; 
+
+	new_node->next = prev_node->next; 
+
+	prev_node->next = new_node; 
+
+	new_node->prev = prev_node; 
+
+	if (new_node->next != NULL) 
+		new_node->next->prev = new_node; 
+} 
+
+/* Given a reference (pointer to pointer) to the head 
+of a DLL and an int, appends a new node at the end */
+void append(Node** head_ref, int new_data) 
+{ 
+	Node* new_node = new Node(); 
+
+	Node* last = *head_ref; 
+
+	new_node->data = new_data; 
+
+	new_node->next = NULL; 
+	if (*head_ref == NULL) 
+	{ 
+		new_node->prev = NULL; 
+		*head_ref = new_node; 
+		return; 
+	} 
+	while (last->next != NULL) 
+		last = last->next; 
+	last->next = new_node; 
+	new_node->prev = last; 
+
+	return; 
+} 
+
+
+void printList(Node* node) 
+{ 
+	Node* last; 
+	cout<<"\nTraversal in forward direction \n"; 
+	while (node != NULL) 
+	{ 
+		cout<<" "<<node->data<<" "; 
+		last = node; 
+		node = node->next; 
+	} 
+
+	cout<<"\nTraversal in reverse direction \n"; 
+	while (last != NULL) 
+	{ 
+		cout<<" "<<last->data<<" "; 
+		last = last->prev; 
+	} 
+} 
+
+int main() 
+{ 
+	Node* head = NULL; 
+	append(&head, 26); 
+	push(&head, 12); 
+	push(&head, 4); 
+
+	append(&head, 9); 
+
+	insertAfter(head->next, 31); 
+
+	cout << "Created DLL is: "; 
+	printList(head); 
+
+	return 0; 
+}