Merge pull request #133 from kiruba-r11/feature-1

Insert at Head of the Doubly Linked Lists

Author: smv1999

Data Structures/Linked Lists/Doubly Linked List/insert_at_begin.cpp

@@ -0,0 +1,80 @@
+/*
+
+This is a Doubly Linked List program which gets a integer data from the user and
+creates a node which is inserted at the beginning to the Linked List.
+
+Since, it is a Doubly Linked List, both the forward and backward traversal is also possible.
+
+
+*/
+
+#include <iostream>
+
+using namespace std;
+
+/*
+
+Node definition:
+	1. Pointer to previous node.
+	2. Integer Data
+	3. Pointer to next node.
+
+*/
+
+class dll_node {
+public:
+	dll_node* prev;
+	int data;
+	dll_node* next;
+};
+
+void createDLL(dll_node* &head) {
+
+	int choice;
+
+	do {
+
+		int data;
+
+		cout << "Enter Data : ";
+		cin >> data;
+
+		dll_node* newNode = new dll_node();
+		newNode->data = data;
+		newNode->prev = NULL;
+		newNode->next = NULL;
+
+		if(head == NULL) {
+			head = newNode;
+		} else {
+			newNode->next = head;
+			head->prev = newNode;
+			head = newNode;
+		}
+
+		cout << "Do you want to continue? (1/0) : ";
+		cin >> choice;
+
+	} while(choice == 1);
+
+
+}
+
+void display(dll_node* head) {
+	cout << "The elements are : ";
+	while(head != NULL) {
+		cout << head->data << " ";
+		head = head->next;
+	}
+	cout << endl;
+}
+
+int main() {
+
+	dll_node* head = NULL;
+
+	createDLL(head);
+	display(head);
+
+	return 0;
+}