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  1. using System;
  2. using System.Collections.Generic;
  3. using System.Diagnostics;
  4. using System.Net.Sockets;
  5. using System.Reflection.Emit;
  6.  
  7.  
  8. namespace UndoRedoFunctionality;
  9.  
  10. ///****************************(Classes)********************************/
  11. class Node
  12. {
  13.     public string action;
  14.     public Node next;
  15.     public Node prev;
  16.  
  17.     public Node(string action)
  18.     {
  19.         this.action = action;
  20.         next = null;
  21.         prev = null;
  22.     }
  23. }
  24.  
  25. class UndoRedo
  26. {
  27.     private Node curr;
  28.  
  29.     public UndoRedo()
  30.     {
  31.         Console.WriteLine("#  You can add actions and use undo/redo  #");
  32.         curr = null;
  33.     }
  34.  
  35.     public void addAction(string action)
  36.     {
  37.         Node newNode = new Node(action);
  38.  
  39.         if (curr != null)
  40.         {
  41.             curr.next = null; // you can't undo the first action
  42.  
  43.             newNode.prev = curr;
  44.             curr.next = newNode;
  45.         }
  46.         curr = newNode;
  47.         Console.Write("Action added: " + curr.action + " -> ");
  48.         display();
  49.     }
  50.  
  51.     public void undo()
  52.     {
  53.         if (curr == null)
  54.         {
  55.             Console.WriteLine("No action to undo");
  56.             return;
  57.         }
  58.         Console.Write("Undo " + curr.action + " -> ");
  59.         curr = curr.prev;
  60.         display();
  61.  
  62.     }
  63.  
  64.     public void redo()
  65.     {
  66.         if (curr == null || curr.next == null)
  67.         {
  68.             Console.WriteLine("No action to redo");
  69.             return;
  70.         }
  71.         Console.Write("Redo " + curr.action + " -> ");
  72.         curr = curr.next;
  73.         display();
  74.  
  75.     }
  76.     public void display()
  77.     {
  78.         if (curr == null)
  79.         {
  80.             Console.WriteLine("No actions to display");
  81.             return;
  82.         }
  83.  
  84.         Node temp = curr;
  85.         while (temp.prev != null)
  86.             temp = temp.prev;
  87.  
  88.         while (temp != curr)
  89.         {
  90.             Console.Write(temp.action + "   ");
  91.             temp = temp.next;
  92.         }
  93.  
  94.         Console.WriteLine(curr.action);
  95.     }
  96. }
  97.  
  98. /********************************************************************/
  99. internal class Program
  100. {
  101.  
  102.     ///-----------------------(funcoins )--------------------------------/
  103.  
  104.     //------------------------------------------------------------------------/
  105.  
  106.     static void Main()
  107.     {
  108.         UndoRedo test = new UndoRedo(); 
  109.         test.addAction("A"); // Action added: A -> A
  110.         test.addAction("B"); // Action added: B -> A   B
  111.         test.addAction("C"); // Action added: C -> A   B   C
  112.         test.addAction("D"); // Action added: D -> A   B   C   D
  113.         test.display(); // A   B   C   D
  114.         test.undo(); // Undo D -> A   B   C
  115.         test.undo(); // Undo C -> A   B
  116.         test.redo(); // Redo C -> A   B   C
  117.         test.undo(); // Undo C -> A   B
  118.         test.undo();  // Undo B -> A
  119.         test.undo(); // Undo A -> No actions to display
  120.         test.undo(); // No actions to undo
  121.         test.display(); // No actions to display
  122.     }
  123.  
  124. }
Success #stdin #stdout 0.07s 28708KB
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Standard input is empty
stdout
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#  You can add actions and use undo/redo  #
Action added: A -> A
Action added: B -> A   B
Action added: C -> A   B   C
Action added: D -> A   B   C   D
A   B   C   D
Undo D -> A   B   C
Undo C -> A   B
Redo B -> A   B   C
Undo C -> A   B
Undo B -> A
Undo A -> No actions to display
No action to undo
No actions to display
https://ideone.com/52NjeE
language:
C# (NET 6.0)
created:
3 days ago
visibility:
public

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