From 62da3ac3ca63975133413b89b38f76ecad6ae797 Mon Sep 17 00:00:00 2001
From: Pranav Ojha <ojhapranav14@gmail.com>
Date: Thu, 12 Oct 2023 11:01:33 +0530
Subject: [PATCH] doubly linked list

---
 C++/doublylinkedlist.cpp | 150 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 C++/doublylinkedlist.cpp

diff --git a/C++/doublylinkedlist.cpp b/C++/doublylinkedlist.cpp
new file mode 100644
index 0000000..9c16aad
--- /dev/null
+++ b/C++/doublylinkedlist.cpp
@@ -0,0 +1,150 @@
+#include <iostream>
+using namespace std;
+
+class Node
+{
+public:
+    int data;
+    Node *prev;
+    Node *next;
+    Node(int x)
+    {
+        data = x;
+        next = NULL;
+        prev = NULL;
+    }
+};
+
+Node *insert()
+{
+    int n;
+    cin >> n;
+    Node *p, *head;
+    for (int i = 0; i < n; i++)
+    {
+        int x;
+        cin >> x;
+        Node *temp = new Node(x);
+
+        if (i == 0)
+        {
+            head = temp;
+            p = head;
+        }
+        else
+        {
+            temp->prev = p;
+            p->next = temp;
+            p = p->next;
+        }
+    }
+    return head;
+}
+
+Node *insertfront(Node *head)
+{
+    int data;
+    cin >> data;
+    Node *temp = new Node(data);
+    temp->next = head;
+    head->prev = temp;
+    head = temp;
+    return head;
+}
+
+Node *insertEnd(Node *head)
+{
+    int data;
+    cin >> data;
+    Node *temp = new Node(data);
+    if (head == NULL)
+    {
+        head = temp;
+    }
+    Node *p = head;
+    while (p->next != NULL)
+    {
+        p = p->next;
+    }
+    p->next = temp;
+    temp->prev = p;
+    return head;
+}
+
+Node *reverse(Node *head)
+{
+    Node *temp = NULL;
+    Node *curr = head;
+    while (curr != NULL)
+    {
+        temp = curr->prev;
+        curr->prev = curr->next;
+        curr->next = temp;
+        curr = curr->prev;
+    }
+    if (temp != NULL)
+        head = temp->prev;
+    return head;
+}
+
+Node *deleteFirst(Node *head)
+{
+    Node *p = head;
+    if (head == NULL || head->next == NULL)
+    {
+        return NULL;
+    }
+    head = p->next;
+    delete p;
+    head->prev = NULL;
+    return head;
+}
+
+Node *deleteEnd(Node *head)
+{
+    Node *p;
+    if (head == NULL || head->next == NULL)
+    {
+        return NULL;
+    }
+    p = head;
+    while (p->next != NULL)
+    {
+        p = p->next;
+    }
+    p->prev->next = NULL;
+    delete p;
+    return head;
+}
+
+void printList(Node *head)
+{
+    Node *p = head;
+    while (p != NULL)
+    {
+        cout << p->data << " ";
+        p = p->next;
+    }
+}
+
+int main()
+{
+    Node *head = insert();
+    printList(head);
+    cout << endl;
+    head = insertfront(head);
+    printList(head);
+    cout << endl;
+    head = insertEnd(head);
+    printList(head);
+    cout << endl;
+    head = reverse(head);
+    printList(head);
+    cout << endl;
+    head = deleteFirst(head);
+    printList(head);
+    cout << endl;
+    head = deleteEnd(head);
+    printList(head);
+    return 0;
+}
\ No newline at end of file