Added functionality to merge two singly linked list (#192)

linked-lists/README.md

@@ -8,6 +8,7 @@
 4. [Circular Linked List](c-or-cpp/circular.cpp)
 5. [Insertion Linked List](c-or-cpp/all-possible-insertion.cpp)
 6. [Josephus Problem Using Circular Linked List](c-or-cpp/josephus-problem.c)
+7. [Merge Two Singly linked List](c-or-cpp/merge.cpp)
 
 ### Java
 

linked-lists/c-or-cpp/merge.cpp

@@ -0,0 +1,117 @@
+#include <iostream>
+
+template <typename T>
+class LinkedList{
+	public:
+		int size = 0;
+		void pushfront(const T& data);
+		T& front();	
+		void popfront();
+		void display();
+		void merge(const LinkedList<T>& other);
+		LinkedList<T>& operator=(const LinkedList<T>& other);
+
+	private:
+		struct node{
+			T data;
+			node* next;
+			node(const T& data): data(data), next(nullptr){}
+		};
+		node* head_ = nullptr;
+};
+
+template <typename T>
+LinkedList<T>& LinkedList<T>::operator=(const LinkedList<T>& other){
+
+	//clearing all node in 'this' list
+	while(head_ != nullptr){
+		this->popfront();
+	}
+	node* current = other.head_;
+	while(current != nullptr){
+		this->pushfront(current->data);
+		current = current->next;
+	}
+	return *this;
+}
+
+template <typename T>
+T& LinkedList<T>::front(){
+	//returns the first node data of the linked list
+
+	return head_->data;
+}
+
+template <typename T>
+void LinkedList<T>::popfront(){
+	//sets the head pointer to nullptr and the next node as the new head
+	
+	//if there is no node then do nothing
+	if(head_ == nullptr) return;
+	if(head_->next == nullptr){
+		delete head_;	
+		head_ = nullptr;
+		--size;
+		return;
+	}
+	node* oldhead = head_;
+	head_ = head_->next;
+	delete oldhead;
+	oldhead = nullptr;
+	size--;
+}
+
+template <typename T>
+void LinkedList<T>::pushfront(const T& data){
+	node* n = new node(data);
+	/*if the list is empty pointer the head pointer to 
+	 newly created node */
+	if(head_ == nullptr){ head_ = n; }
+	else{
+		n->next = head_;
+		head_ = n;
+	}
+	size++;
+}
+
+
+template <typename T>
+void LinkedList<T>::display(){
+	node* thru = head_;
+	while(thru != nullptr){
+		std::cout << thru->data << std::endl;
+		thru = thru->next;
+	}
+}
+
+template <typename T>
+void LinkedList<T>::merge(const LinkedList<T>& other) {
+	LinkedList<T> l1 ;
+	l1 = other;
+	while(l1.size > 0){
+		//inserting the data of the other list to the current list
+		this->pushfront(l1.front());
+		//removing the first node of the list
+		//this will continue until there is no more node in the other list
+		l1.popfront();
+	}
+}
+
+int main(){
+	LinkedList<int> l1, l2;
+
+	l1.pushfront(1);
+	l1.pushfront(2);
+	l1.pushfront(3);
+	l2.pushfront(21);
+	l2.pushfront(11);
+	l2.pushfront(31);
+
+	l2.merge(l1);
+	
+	std::cout << "AFTER MERGE" << std::endl;
+	std::cout << "LIST 1" << std::endl;
+	l1.display();
+	std::cout << "LIST 2" << std::endl;
+	l2.display();
+}