Fix : add reverse doubly ll function

CONTRIBUTORS.md

@@ -46,4 +46,5 @@
 | Helen Sahith Sadhe |<a href="https://github.com/helensahith">helensahith</a>|
 | Vanshika Rathod |<a href="https://github.com/vanshikaaaaaaaa">vanshika</a>|
 | Sujit Manojrao Nirmal |<a href="https://github.com/Blacksujit">helensahith</a>|
+| Mahendra Pratap Verma |<a href="https://github.com/Mahendra2611">Mahendra2611</a>|
 

c++/ReverseDoublyLL.cpp

@@ -0,0 +1,55 @@
+#include<iostream>
+using namespace std;
+class Node{
+    public:
+    int data;
+Node* next = NULL;
+Node* prev = NULL;
+Node(int d){
+    this->data = d;
+    this->next = NULL;
+    this->prev =  NULL;
+}
+};
+void print(Node* &head){
+    Node* temp = head;
+    while(temp != NULL){
+        cout<<temp->data<<" ";
+        temp = temp->next;
+    }
+    cout<<endl;
+}
+void insert(Node* &head,int d){
+    Node* temp  = new Node(d);
+temp->next = head;
+head->prev = temp;
+head = temp;
+}
+Node* reverse(Node* &head){
+    Node* temp = head;
+
+while(temp != NULL){
+    Node* store = temp->next;
+     temp->next = temp->prev;
+temp->prev = store;
+head = temp;
+temp = store;
+}
+//for using this condition we have to change print function temp = temp->next to temp = temp->prev
+// while(temp != NULL){
+//     head = temp;
+//     temp = temp->next;
+// }
+return head;
+}
+int main(){
+Node* node1 = new Node(7);
+Node* head = node1;
+insert(head,5);
+insert(head,3);
+insert(head,1);
+print(head);
+Node* result = reverse(head);
+print(result);
+  return 0;
+}