Konvertieren Sie einen Binärbaum in eine kreisförmige Liste mit doppelten Verknüpfungen

Konvertieren Sie einen Binärbaum in eine kreisförmige Liste mit doppelten Verknüpfungen
Probieren Sie es bei GfG Practice aus Baum zum Auflisten #practiceLinkDiv { display: none !important; }

Gegeben a Binärer Baum Wandeln Sie es in ein um Zirkuläre doppelt verknüpfte Liste (In-Place).  

  • Die linken und rechten Zeiger in Knoten sollen als vorherige bzw. nächste Zeiger in der konvertierten kreisförmig verknüpften Liste verwendet werden.
  • Die Reihenfolge der Knoten in der Liste muss mit der in Inorder für den angegebenen Binärbaum übereinstimmen.
  • Der erste Knoten der Inorder-Traversierung muss der Kopfknoten der kreisförmigen Liste sein.

Beispiele:

Empfohlene Praxis Binärbaum zu CDLL Probieren Sie es aus!

Konvertieren Sie einen Binärbaum mithilfe der Rekursion in eine kreisförmige Liste mit doppelten Verknüpfungen:

Die Idee besteht darin, eine Allzweckfunktion zu erstellen, die zwei gegebene zirkuläre Doppellisten verkettet

Führen Sie die folgenden Schritte aus, um das Problem zu lösen:

  • Konvertieren Sie den linken Teilbaum rekursiv in eine zirkuläre DLL. Sei die konvertierte Liste leftList .
  • Konvertieren Sie den rechten Teilbaum rekursiv in eine zirkuläre DLL. Sei die konvertierte Liste rightList
  • Erstellen Sie eine kreisförmig verknüpfte Liste der Wurzeln des Baums und legen Sie fest, dass die linken und rechten Wurzelpunkte auf sich selbst zeigen. 
  • Verketten leftList mit der Liste des einzelnen Wurzelknotens. 
  • Verketten Sie die im obigen Schritt erstellte Liste mit rightList .

Notiz: Der obige Ansatz durchläuft den Baum im Postorder-Stil. Wir können auch in der Reihenfolge durchqueren. Wir können zuerst den linken Teilbaum und die Wurzel verketten, dann für den rechten Teilbaum wiederholen und das Ergebnis mit der Verkettung der linken Wurzel verketten.

Wie verketten Sie zwei zirkuläre DLLs?  

  • Holen Sie sich den letzten Knoten der linken Liste. Das Abrufen des letzten Knotens ist eine O(1)-Operation, da der vorherige Zeiger des Kopfes auf den letzten Knoten der Liste zeigt.
  • Verbinden Sie es mit dem ersten Knoten der rechten Liste
  • Holen Sie sich den letzten Knoten der zweiten Liste
  • Verbinden Sie es mit dem Kopf der Liste.

Nachfolgend finden Sie Implementierungen der oben genannten Idee:

C++
   // C++ Program to convert a Binary Tree   // to a Circular Doubly Linked List   #include          using     namespace     std  ;   // To represents a node of a Binary Tree   struct     Node     {      struct     Node     *  left       *  right  ;      int     data  ;   };   // A function that appends rightList at the end   // of leftList.   Node  *     concatenate  (  Node  *     leftList       Node  *     rightList  )   {      // If either of the list is empty      // then return the other list      if     (  leftList     ==     NULL  )      return     rightList  ;      if     (  rightList     ==     NULL  )      return     leftList  ;      // Store the last Node of left List      Node  *     leftLast     =     leftList  ->  left  ;      // Store the last Node of right List      Node  *     rightLast     =     rightList  ->  left  ;      // Connect the last node of Left List      // with the first Node of the right List      leftLast  ->  right     =     rightList  ;      rightList  ->  left     =     leftLast  ;      // Left of first node points to      // the last node in the list      leftList  ->  left     =     rightLast  ;      // Right of last node refers to the first      // node of the List      rightLast  ->  right     =     leftList  ;      return     leftList  ;   }   // Function converts a tree to a circular Linked List   // and then returns the head of the Linked List   Node  *     bTreeToCList  (  Node  *     root  )   {      if     (  root     ==     NULL  )      return     NULL  ;      // Recursively convert left and right subtrees      Node  *     left     =     bTreeToCList  (  root  ->  left  );      Node  *     right     =     bTreeToCList  (  root  ->  right  );      // Make a circular linked list of single node      // (or root). To do so make the right and      // left pointers of this node point to itself      root  ->  left     =     root  ->  right     =     root  ;      // Step 1 (concatenate the left list with the list      // with single node i.e. current node)      // Step 2 (concatenate the returned list with the      // right List)      return     concatenate  (  concatenate  (  left       root  )     right  );   }   // Display Circular Link List   void     displayCList  (  Node  *     head  )   {      cout      < <     'Circular Linked List is :  n  '  ;      Node  *     itr     =     head  ;      do     {      cout      < <     itr  ->  data      < <     ' '  ;      itr     =     itr  ->  right  ;      }     while     (  head     !=     itr  );      cout      < <     '  n  '  ;   }   // Create a new Node and return its address   Node  *     newNode  (  int     data  )   {      Node  *     temp     =     new     Node  ();      temp  ->  data     =     data  ;      temp  ->  left     =     temp  ->  right     =     NULL  ;      return     temp  ;   }   // Driver Program to test above function   int     main  ()   {      Node  *     root     =     newNode  (  10  );      root  ->  left     =     newNode  (  12  );      root  ->  right     =     newNode  (  15  );      root  ->  left  ->  left     =     newNode  (  25  );      root  ->  left  ->  right     =     newNode  (  30  );      root  ->  right  ->  left     =     newNode  (  36  );      Node  *     head     =     bTreeToCList  (  root  );      displayCList  (  head  );      return     0  ;   }   // This code is contributed by Aditya Kumar (adityakumar129)   
C
   // C Program to convert a Binary Tree   // to a Circular Doubly Linked List   #include         #include         // To represents a node of a Binary Tree   typedef     struct     Node     {      struct     Node     *  left       *  right  ;      int     data  ;   }     Node  ;   // A function that appends rightList at the end   // of leftList.   Node  *     concatenate  (  Node  *     leftList       Node  *     rightList  )   {      // If either of the list is empty      // then return the other list      if     (  leftList     ==     NULL  )      return     rightList  ;      if     (  rightList     ==     NULL  )      return     leftList  ;      // Store the last Node of left List      Node  *     leftLast     =     leftList  ->  left  ;      // Store the last Node of right List      Node  *     rightLast     =     rightList  ->  left  ;      // Connect the last node of Left List      // with the first Node of the right List      leftLast  ->  right     =     rightList  ;      rightList  ->  left     =     leftLast  ;      // Left of first node points to      // the last node in the list      leftList  ->  left     =     rightLast  ;      // Right of last node refers to the first      // node of the List      rightLast  ->  right     =     leftList  ;      return     leftList  ;   }   // Function converts a tree to a circular Linked List   // and then returns the head of the Linked List   Node  *     bTreeToCList  (  Node  *     root  )   {      if     (  root     ==     NULL  )      return     NULL  ;      // Recursively convert left and right subtrees      Node  *     left     =     bTreeToCList  (  root  ->  left  );      Node  *     right     =     bTreeToCList  (  root  ->  right  );      // Make a circular linked list of single node      // (or root). To do so make the right and      // left pointers of this node point to itself      root  ->  left     =     root  ->  right     =     root  ;      // Step 1 (concatenate the left list with the list      // with single node i.e. current node)      // Step 2 (concatenate the returned list with the      // right List)      return     concatenate  (  concatenate  (  left       root  )     right  );   }   // Display Circular Link List   void     displayCList  (  Node  *     head  )   {      printf  (  'Circular Linked List is :  n  '  );      Node  *     itr     =     head  ;      do     {      printf  (  '%d '       itr  ->  data  );      itr     =     itr  ->  right  ;      }     while     (  head     !=     itr  );      printf  (  '  n  '  );   }   // Create a new Node and return its address   Node  *     newNode  (  int     data  )   {      Node  *     temp     =     (  Node  *  )  malloc  (  sizeof  (  Node  ));      temp  ->  data     =     data  ;      temp  ->  left     =     temp  ->  right     =     NULL  ;      return     temp  ;   }   // Driver Program to test above function   int     main  ()   {      Node  *     root     =     newNode  (  10  );      root  ->  left     =     newNode  (  12  );      root  ->  right     =     newNode  (  15  );      root  ->  left  ->  left     =     newNode  (  25  );      root  ->  left  ->  right     =     newNode  (  30  );      root  ->  right  ->  left     =     newNode  (  36  );      Node  *     head     =     bTreeToCList  (  root  );      displayCList  (  head  );      return     0  ;   }   // This code is contributed by Aditya Kumar (adityakumar129)   
Java
   // Java Program to convert a Binary Tree to a   // Circular Doubly Linked List   // Node class represents a Node of a Tree   class   Node     {      int     val  ;      Node     left       right  ;      public     Node  (  int     val  )      {      this  .  val     =     val  ;      left     =     right     =     null  ;      }   }   // A class to represent a tree   class   Tree     {      Node     root  ;      public     Tree  ()     {     root     =     null  ;     }      // concatenate both the lists and returns the head      // of the List      public     Node     concatenate  (  Node     leftList       Node     rightList  )      {      // If either of the list is empty then      // return the other list      if     (  leftList     ==     null  )      return     rightList  ;      if     (  rightList     ==     null  )      return     leftList  ;      // Store the last Node of left List      Node     leftLast     =     leftList  .  left  ;      // Store the last Node of right List      Node     rightLast     =     rightList  .  left  ;      // Connect the last node of Left List      // with the first Node of the right List      leftLast  .  right     =     rightList  ;      rightList  .  left     =     leftLast  ;      // left of first node refers to      // the last node in the list      leftList  .  left     =     rightLast  ;      // Right of last node refers to the first      // node of the List      rightLast  .  right     =     leftList  ;      // Return the Head of the List      return     leftList  ;      }      // Method converts a tree to a circular      // Link List and then returns the head      // of the Link List      public     Node     bTreeToCList  (  Node     root  )      {      if     (  root     ==     null  )      return     null  ;      // Recursively convert left and right subtrees      Node     left     =     bTreeToCList  (  root  .  left  );      Node     right     =     bTreeToCList  (  root  .  right  );      // Make a circular linked list of single node      // (or root). To do so make the right and      // left pointers of this node point to itself      root  .  left     =     root  .  right     =     root  ;      // Step 1 (concatenate the left list with the list      // with single node i.e. current node)      // Step 2 (concatenate the returned list with the      // right List)      return     concatenate  (  concatenate  (  left       root  )     right  );      }      // Display Circular Link List      public     void     display  (  Node     head  )      {      System  .  out  .  println  (  'Circular Linked List is :'  );      Node     itr     =     head  ;      do     {      System  .  out  .  print  (  itr  .  val     +     ' '  );      itr     =     itr  .  right  ;      }     while     (  itr     !=     head  );      System  .  out  .  println  ();      }   }   // Driver Code   class   Main     {      public     static     void     main  (  String     args  []  )      {      // Build the tree      Tree     tree     =     new     Tree  ();      tree  .  root     =     new     Node  (  10  );      tree  .  root  .  left     =     new     Node  (  12  );      tree  .  root  .  right     =     new     Node  (  15  );      tree  .  root  .  left  .  left     =     new     Node  (  25  );      tree  .  root  .  left  .  right     =     new     Node  (  30  );      tree  .  root  .  right  .  left     =     new     Node  (  36  );      // head refers to the head of the Link List      Node     head     =     tree  .  bTreeToCList  (  tree  .  root  );      // Display the Circular LinkedList      tree  .  display  (  head  );      }   }   
Python3
   # Python3 Program to convert a Binary   # Tree to a Circular Doubly Linked List   class   newNode  :   def   __init__  (  self     data  ):   self  .  data   =   data   self  .  left   =   self  .  right   =   None   # A function that appends rightList   # at the end of leftList.   def   concatenate  (  leftList     rightList  ):   # If either of the list is empty   # then return the other list   if   (  leftList   ==   None  ):   return   rightList   if   (  rightList   ==   None  ):   return   leftList   # Store the last Node of left List   leftLast   =   leftList  .  left   # Store the last Node of right List   rightLast   =   rightList  .  left   # Connect the last node of Left List   # with the first Node of the right List   leftLast  .  right   =   rightList   rightList  .  left   =   leftLast   # Left of first node points to   # the last node in the list   leftList  .  left   =   rightLast   # Right of last node refers to   # the first node of the List   rightLast  .  right   =   leftList   return   leftList   # Function converts a tree to a circular   # Linked List and then returns the head   # of the Linked List   def   bTreeToCList  (  root  ):   if   (  root   ==   None  ):   return   None   # Recursively convert left and   # right subtrees   left   =   bTreeToCList  (  root  .  left  )   right   =   bTreeToCList  (  root  .  right  )   # Make a circular linked list of single   # node (or root). To do so make the   # right and left pointers of this node   # point to itself   root  .  left   =   root  .  right   =   root   # Step 1 (concatenate the left list   # with the list with single   # node i.e. current node)   # Step 2 (concatenate the returned list   # with the right List)   return   concatenate  (  concatenate  (  left     root  )   right  )   # Display Circular Link List   def   displayCList  (  head  ):   print  (  'Circular Linked List is :'  )   itr   =   head   first   =   1   while   (  head   !=   itr   or   first  ):   print  (  itr  .  data     end  =  ' '  )   itr   =   itr  .  right   first   =   0   print  ()   # Driver Code   if   __name__   ==   '__main__'  :   root   =   newNode  (  10  )   root  .  left   =   newNode  (  12  )   root  .  right   =   newNode  (  15  )   root  .  left  .  left   =   newNode  (  25  )   root  .  left  .  right   =   newNode  (  30  )   root  .  right  .  left   =   newNode  (  36  )   head   =   bTreeToCList  (  root  )   displayCList  (  head  )   # This code is contributed by PranchalK   
C#
   // C# Program to convert a Binary Tree   // to a Circular Doubly Linked List   using     System  ;   // Node class represents a Node of a Tree   public     class     Node     {      public     int     val  ;      public     Node     left       right  ;      public     Node  (  int     val  )      {      this  .  val     =     val  ;      left     =     right     =     null  ;      }   }   // A class to represent a tree   public     class     Tree     {      internal     Node     root  ;      public     Tree  ()     {     root     =     null  ;     }      // concatenate both the lists      // and returns the head of the List      public     virtual     Node     concatenate  (  Node     leftList        Node     rightList  )      {      // If either of the list is empty      // then return the other list      if     (  leftList     ==     null  )     {      return     rightList  ;      }      if     (  rightList     ==     null  )     {      return     leftList  ;      }      // Store the last Node of left List      Node     leftLast     =     leftList  .  left  ;      // Store the last Node of right List      Node     rightLast     =     rightList  .  left  ;      // Connect the last node of Left List      // with the first Node of the right List      leftLast  .  right     =     rightList  ;      rightList  .  left     =     leftLast  ;      // left of first node refers to      // the last node in the list      leftList  .  left     =     rightLast  ;      // Right of last node refers to      // the first node of the List      rightLast  .  right     =     leftList  ;      // Return the Head of the List      return     leftList  ;      }      // Method converts a tree to a circular      // Link List and then returns the head      // of the Link List      public     virtual     Node     bTreeToCList  (  Node     root  )      {      if     (  root     ==     null  )     {      return     null  ;      }      // Recursively convert left      // and right subtrees      Node     left     =     bTreeToCList  (  root  .  left  );      Node     right     =     bTreeToCList  (  root  .  right  );      // Make a circular linked list of single      // node (or root). To do so make the      // right and left pointers of this node      // point to itself      root  .  left     =     root  .  right     =     root  ;      // Step 1 (concatenate the left list with      // the list with single node      // i.e. current node)      // Step 2 (concatenate the returned list      // with the right List)      return     concatenate  (  concatenate  (  left       root  )     right  );      }      // Display Circular Link List      public     virtual     void     display  (  Node     head  )      {      Console  .  WriteLine  (  'Circular Linked List is :'  );      Node     itr     =     head  ;      do     {      Console  .  Write  (  itr  .  val     +     ' '  );      itr     =     itr  .  right  ;      }     while     (  itr     !=     head  );      Console  .  WriteLine  ();      }   }   // Driver Code   public     class     GFG     {      public     static     void     Main  (  string  []     args  )      {      // Build the tree      Tree     tree     =     new     Tree  ();      tree  .  root     =     new     Node  (  10  );      tree  .  root  .  left     =     new     Node  (  12  );      tree  .  root  .  right     =     new     Node  (  15  );      tree  .  root  .  left  .  left     =     new     Node  (  25  );      tree  .  root  .  left  .  right     =     new     Node  (  30  );      tree  .  root  .  right  .  left     =     new     Node  (  36  );      // head refers to the head of the Link List      Node     head     =     tree  .  bTreeToCList  (  tree  .  root  );      // Display the Circular LinkedList      tree  .  display  (  head  );      }   }   // This code is contributed by Shrikant13   
JavaScript
    <  script  >   // javascript Program to convert a Binary Tree to a   // Circular Doubly Linked List   // Node class represents a Node of a Tree   class     Node     {      constructor  (  val  )     {      this  .  val     =     val  ;      this  .  left     =     null  ;      this  .  right     =     null  ;      }   }   // A class to represent a       var     root     =     null  ;      // concatenate both the lists and returns the head      // of the List      function     concatenate  (  leftList       rightList  )     {      // If either of the list is empty then      // return the other list      if     (  leftList     ==     null  )      return     rightList  ;      if     (  rightList     ==     null  )      return     leftList  ;      // Store the last Node of left List      var     leftLast     =     leftList  .  left  ;      // Store the last Node of right List      var     rightLast     =     rightList  .  left  ;      // Connect the last node of Left List      // with the first Node of the right List      leftLast  .  right     =     rightList  ;      rightList  .  left     =     leftLast  ;      // left of first node refers to      // the last node in the list      leftList  .  left     =     rightLast  ;      // Right of last node refers to the first      // node of the List      rightLast  .  right     =     leftList  ;      // Return the Head of the List      return     leftList  ;      }      // Method converts a to a circular      // Link List and then returns the head      // of the Link List      function     bTreeToCList  (  root  )     {      if     (  root     ==     null  )      return     null  ;      // Recursively convert left and right subtrees      var     left     =     bTreeToCList  (  root  .  left  );      var     right     =     bTreeToCList  (  root  .  right  );      // Make a circular linked list of single node      // (or root). To do so make the right and      // left pointers of this node point to itself      root  .  left     =     root  .  right     =     root  ;      // Step 1 (concatenate the left list with the list      // with single node i.e. current node)      // Step 2 (concatenate the returned list with the      // right List)      return     concatenate  (  concatenate  (  left       root  )     right  );      }      // Display Circular Link List      function     display  (  head  )     {      document  .  write  (  'Circular Linked List is :  
'
); var itr = head ; do { document . write ( itr . val + ' ' ); itr = itr . right ; } while ( itr != head ); document . write (); } // Driver Code // Build the root = new Node ( 10 ); root . left = new Node ( 12 ); root . right = new Node ( 15 ); root . left . left = new Node ( 25 ); root . left . right = new Node ( 30 ); root . right . left = new Node ( 36 ); // head refers to the head of the Link List var head = bTreeToCList ( root ); // Display the Circular LinkedList display ( head ); // This code contributed by umadevi9616 < /script>

Ausgabe
Circular Linked List is : 25 12 30 10 36 15  

Zeitkomplexität: AN) Da jeder Knoten höchstens einmal besucht wird.
Nebenraum: O(log N) Der zusätzliche Platz wird im Rekursionsaufrufstapel verwendet, der bis zu einer maximalen Größe von logN anwachsen kann, da es sich um einen Binärbaum handelt.

Konvertieren Sie einen Binärbaum durch Inorder Traversal in eine kreisförmige Doppelverknüpfungsliste:

Die Idee besteht darin, den Binärbaum in der richtigen Reihenfolge zu durchlaufen. Verfolgen Sie beim Durchlaufen der Reihenfolge den zuvor besuchten Knoten beispielsweise in einer Variablen vorh . Machen Sie für jeden besuchten Knoten den nächsten Knoten vorh und setzen Sie den vorherigen Knoten als vorh .

Führen Sie die folgenden Schritte aus, um das Problem zu lösen:

  • Konvertieren Sie zunächst den Binärbaum in eine doppelt verknüpfte Liste. Weitere Informationen finden Sie in diesem Beitrag Konvertieren Sie einen bestimmten Binärbaum in eine doppelt verknüpfte Liste .
  • Konvertieren Sie nun diese doppelt verknüpfte Liste in eine kreisförmige doppelt verknüpfte Liste, indem Sie den ersten und letzten Knoten verbinden.

Nachfolgend finden Sie die Umsetzung des oben genannten Ansatzes.

C++
   // A C++ program for in-place conversion of Binary Tree to   // CDLL   #include          using     namespace     std  ;   /* A binary tree node has - data  left and right pointers    */   struct     Node     {      int     data  ;      Node  *     left  ;      Node  *     right  ;   };   // A utility function that converts given binary tree to   // a doubly linked list   // root --> the root of the binary tree   // head --> head of the created doubly linked list   Node  *     BTree2DoublyLinkedList  (  Node  *     root       Node  **     head  )   {      // Base case      if     (  root     ==     NULL  )      return     root  ;      // Initialize previously visited node as NULL. This is      // static so that the same value is accessible in all      // recursive calls      static     Node  *     prev     =     NULL  ;      // Recursively convert left subtree      BTree2DoublyLinkedList  (  root  ->  left       head  );      // Now convert this node      if     (  prev     ==     NULL  )      *  head     =     root  ;      else     {      root  ->  left     =     prev  ;      prev  ->  right     =     root  ;      }      prev     =     root  ;      // Finally convert right subtree      BTree2DoublyLinkedList  (  root  ->  right       head  );      return     prev  ;   }   // A simple recursive function to convert a given Binary   // tree to Circular Doubly Linked List using a utility   // function root --> Root of Binary Tree tail --> Pointer to   // tail node of created circular doubly linked list   Node  *     BTree2CircularDoublyLinkedList  (  Node  *     root  )   {      Node  *     head     =     NULL  ;      Node  *     tail     =     BTree2DoublyLinkedList  (  root       &  head  );      // make the changes to convert a DLL to CDLL      tail  ->  right     =     head  ;      head  ->  left     =     tail  ;      // return the head of the created CDLL      return     head  ;   }   /* Helper function that allocates a new node with the   given data and NULL left and right pointers. */   Node  *     newNode  (  int     data  )   {      Node  *     new_node     =     new     Node  ;      new_node  ->  data     =     data  ;      new_node  ->  left     =     new_node  ->  right     =     NULL  ;      return     (  new_node  );   }   /* Function to print nodes in a given circular doubly linked    * list */   void     printList  (  Node  *     head  )   {      if     (  head     ==     NULL  )      return  ;      Node  *     ptr     =     head  ;      do     {      cout      < <     ptr  ->  data      < <     ' '  ;      ptr     =     ptr  ->  right  ;      }     while     (  ptr     !=     head  );   }   /* Driver program to test above functions*/   int     main  ()   {      // Let us create the tree shown in above diagram      Node  *     root     =     newNode  (  10  );      root  ->  left     =     newNode  (  12  );      root  ->  right     =     newNode  (  15  );      root  ->  left  ->  left     =     newNode  (  25  );      root  ->  left  ->  right     =     newNode  (  30  );      root  ->  right  ->  left     =     newNode  (  36  );      // Convert to DLL      Node  *     head     =     BTree2CircularDoublyLinkedList  (  root  );      // Print the converted list      printList  (  head  );      return     0  ;   }   // This code was contributed by Abhijeet   // Kumar(abhijeet19403)   
Java
   // A Java program for in-place conversion of Binary Tree to   // CDLL   // A binary tree node has - data left pointer and right   // pointer   class   Node     {      int     data  ;      Node     left       right  ;      public     Node  (  int     data  )      {      this  .  data     =     data  ;      left     =     right     =     null  ;      }   }   class   BinaryTree     {      Node     root  ;      // head --> Pointer to head node of created doubly      // linked list      Node     head  ;      // Initialize previously visited node as NULL. This is      // static so that the same value is accessible in all      // recursive calls      static     Node     prev     =     null  ;      // A simple utility recursive function to convert a      // given Binary tree to Doubly Linked List root --> Root      // of Binary Tree      void     BTree2DoublyLinkedList  (  Node     root  )      {      // Base case      if     (  root     ==     null  )      return  ;      // Recursively convert left subtree      BTree2DoublyLinkedList  (  root  .  left  );      // Now convert this node      if     (  prev     ==     null  )      head     =     root  ;      else     {      root  .  left     =     prev  ;      prev  .  right     =     root  ;      }      prev     =     root  ;      // Finally convert right subtree      BTree2DoublyLinkedList  (  root  .  right  );      }      // A simple function to convert a given binary tree to      // Circular doubly linked list      // using a utility function      void     BTree2CircularDoublyLinkedList  (  Node     root  )      {      BTree2DoublyLinkedList  (  root  );      // make the changes to convert a DLL to CDLL      prev  .  right     =     head  ;      head  .  left     =     prev  ;      }      /* Function to print nodes in a given doubly linked list    */      void     printList  (  Node     node  )      {      if     (  node     ==     null  )      return  ;      Node     curr     =     node  ;      do     {      System  .  out  .  print  (  curr  .  data     +     ' '  );      curr     =     curr  .  right  ;      }     while     (  curr     !=     node  );      }      // Driver program to test above functions      public     static     void     main  (  String  []     args  )      {      // Let us create the tree as shown in above diagram      BinaryTree     tree     =     new     BinaryTree  ();      tree  .  root     =     new     Node  (  10  );      tree  .  root  .  left     =     new     Node  (  12  );      tree  .  root  .  right     =     new     Node  (  15  );      tree  .  root  .  left  .  left     =     new     Node  (  25  );      tree  .  root  .  left  .  right     =     new     Node  (  30  );      tree  .  root  .  right  .  left     =     new     Node  (  36  );      // convert to DLL      tree  .  BTree2CircularDoublyLinkedList  (  tree  .  root  );      // Print the converted List      tree  .  printList  (  tree  .  head  );      }   }   // This code has been contributed by Abhijeet   // Kumar(abhijeet19403)   
Python
   # A python program for in-place conversion of Binary Tree to DLL   # A binary tree node has data left pointers and right pointers   class   Node  :   def   __init__  (  self     val  ):   self  .  data   =   val   self  .  left   =   None   self  .  right   =   None   # head --> Pointer to head node of created doubly linked list   head   =   None   # Initialize previously visited node as NULL. This is   # so that the same value is accessible in all recursive   # calls   prev   =   None   # A simple recursive function to convert a given Binary tree   # to Doubly Linked List   # root --> Root of Binary Tree   def   BinaryTree2DoubleLinkedList  (  root  ):   # Base case   if   (  root   ==   None  ):   return   # Recursively convert left subtree   BinaryTree2DoubleLinkedList  (  root  .  left  )   # Now convert this node   global   prev     head   if   (  prev   ==   None  ):   head   =   root   else  :   root  .  left   =   prev   prev  .  right   =   root   prev   =   root   # Finally convert right subtree   BinaryTree2DoubleLinkedList  (  root  .  right  )   # Function to print nodes in a given doubly linked list   def   printList  (  node  ):   while   (  node   !=   None  ):   print  (  node  .  data  )   node   =   node  .  right   # Driver program to test above functions   # Let us create the tree as shown in above diagram   root   =   Node  (  10  )   root  .  left   =   Node  (  12  )   root  .  right   =   Node  (  15  )   root  .  left  .  left   =   Node  (  25  )   root  .  left  .  right   =   Node  (  30  )   root  .  right  .  left   =   Node  (  36  )   # convert to DLL   BinaryTree2DoubleLinkedList  (  root  )   # Print the converted List   printList  (  head  )   # This code is contributed by adityamaharshi21.   
C#
   // A C# program for in-place conversion of Binary Tree to   // CDLL   using     System  ;   public     class     Node     {      public     int     data  ;      public     Node     left       right  ;      public     Node  (  int     data  )      {      this  .  data     =     data  ;      left     =     right     =     null  ;      }   }   public     class     BinaryTree     {      Node     root  ;      // head --> Pointer to head node of created doubly      // linked list      Node     head  ;      // Initialize previously visited node as NULL. This is      // static so that the same value is accessible in all      // recursive calls      static     Node     prev     =     null  ;      // A simple utility recursive function to convert a      // given Binary tree to Doubly Linked List root --> Root      // of Binary Tree      void     BTree2DoublyLinkedList  (  Node     root  )      {      // Base case      if     (  root     ==     null  )      return  ;      // Recursively convert left subtree      BTree2DoublyLinkedList  (  root  .  left  );      // Now convert this node      if     (  prev     ==     null  )      head     =     root  ;      else     {      root  .  left     =     prev  ;      prev  .  right     =     root  ;      }      prev     =     root  ;      // Finally convert right subtree      BTree2DoublyLinkedList  (  root  .  right  );      }      // A simple function to convert a given binary tree to      // Circular doubly linked list      // using a utility function      void     BTree2CircularDoublyLinkedList  (  Node     root  )      {      BTree2DoublyLinkedList  (  root  );      // make the changes to convert a DLL to CDLL      prev  .  right     =     head  ;      head  .  left     =     prev  ;      }      /* Function to print nodes in a given doubly linked list    */      void     printList  (  Node     node  )      {      if     (  node     ==     null  )      return  ;      Node     curr     =     node  ;      do     {      Console  .  Write  (  curr  .  data     +     ' '  );      curr     =     curr  .  right  ;      }     while     (  curr     !=     node  );      }      static     public     void     Main  ()      {      // Let us create the tree as shown in above diagram      BinaryTree     tree     =     new     BinaryTree  ();      tree  .  root     =     new     Node  (  10  );      tree  .  root  .  left     =     new     Node  (  12  );      tree  .  root  .  right     =     new     Node  (  15  );      tree  .  root  .  left  .  left     =     new     Node  (  25  );      tree  .  root  .  left  .  right     =     new     Node  (  30  );      tree  .  root  .  right  .  left     =     new     Node  (  36  );      // convert to DLL      tree  .  BTree2CircularDoublyLinkedList  (  tree  .  root  );      // Print the converted List      tree  .  printList  (  tree  .  head  );      }   }   // This code is contributed by lokesh(lokeshmvs21).   
JavaScript
   // A javascript program for in-place conversion of Binary Tree to DLL   // A binary tree node has data left pointers and right pointers   class     Node     {      constructor  (  val  )     {      this  .  data     =     val  ;      this  .  left     =     null  ;      this  .  right     =     null  ;      }   }   var     root  ;   // head --> Pointer to head node of created doubly linked list   var     head  ;   // Initialize previously visited node as NULL. This is   // so that the same value is accessible in all recursive   // calls   var     prev     =     null  ;   // A simple recursive function to convert a given Binary tree   // to Doubly Linked List   // root --> Root of Binary Tree   function     BinaryTree2DoubleLinkedList  (  root  )   {      // Base case      if     (  root     ==     null  )      return  ;          // Recursively convert left subtree      BinaryTree2DoubleLinkedList  (  root  .  left  );          // Now convert this node      if     (  prev     ==     null  )      head     =     root  ;      else     {      root  .  left     =     prev  ;      prev  .  right     =     root  ;      }      prev     =     root  ;          // Finally convert right subtree      BinaryTree2DoubleLinkedList  (  root  .  right  );   }   /* Function to print nodes in a given doubly linked list */   function     printList  (  node  )     {      while     (  node     !=     null  )     {      console  .  log  (  node  .  data     +     ' '  );      node     =     node  .  right  ;      }   }   // Driver program to test above functions   // Let us create the tree as shown in above diagram   root     =     new     Node  (  10  );   root  .  left     =     new     Node  (  12  );   root  .  right     =     new     Node  (  15  );   root  .  left  .  left     =     new     Node  (  25  );   root  .  left  .  right     =     new     Node  (  30  );   root  .  right  .  left     =     new     Node  (  36  );   // convert to DLL   BinaryTree2DoubleLinkedList  (  root  );   // Print the converted List   printList  (  head  );   // This code is contributed by ishankhandelwals.   

Ausgabe
25 12 30 10 36 15  

Zeitkomplexität: O(N) Da jeder Knoten höchstens einmal besucht wird.
Nebenraum: O(log N) Der zusätzliche Platz wird im rekursiven Funktionsaufrufstapel verwendet, der bis zu einer maximalen Größe von logN anwachsen kann.

Dieser Ansatz wurde beigesteuert von Abhijeet Kumar