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  1. #include <iostream>
  2.  
  3. // For simplicity, keeping everything public
  4. template<class T>
  5. class Node
  6. {
  7. public:
  8.   Node(T data) : data(data), prev(nullptr), next(nullptr) {}
  9.  
  10.   T data;
  11.   Node* prev;
  12.   Node* next;
  13. };
  14.  
  15. template<class T>
  16. class MyLinkedList
  17. {
  18. public:
  19.   Node<T>* head;
  20.   Node<T>* tail;
  21.  
  22.   MyLinkedList() : head(nullptr), tail(nullptr) {}
  23.  
  24.   void Add(T data)
  25.   {
  26.   	Node<T>* newData = new Node<T>(data);
  27.  
  28.   	if(head == nullptr) { head = tail = newData; }
  29.   	else 
  30.   	{
  31.   		newData->prev = tail;
  32.   		tail->next = newData;
  33.   		tail = newData;
  34.   	}
  35.   }
  36.  
  37.   void Print()
  38.   {
  39.   	Node<int>* ptr = head;
  40. 	while(ptr != nullptr)
  41. 	{
  42. 		std::cout << ptr->data << "\n";
  43. 		ptr = ptr->next;
  44. 	}
  45.   }
  46.  
  47.   void Reverse()
  48.   {
  49.   	// How would you implement this in O(1)?
  50.   	std::swap(head, tail);
  51.   }
  52. };
  53.  
  54. int main() {
  55. 	MyLinkedList<int> list;
  56. 	for(int i = 1; i <= 10; ++i) list.Add(i);
  57. 	list.Print();
  58.  
  59. 	std::cout << "\nSwapping the list...\n";
  60. 	list.Reverse();
  61.  
  62. 	list.Print();
  63.  
  64. 	return 0;
  65. }
Success #stdin #stdout 0s 3456KB
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Swapping the list...
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https://ideone.com/c1HebO
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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