Liste chaînée déroulée | Ensemble 1 (Introduction)

Liste chaînée déroulée | Ensemble 1 (Introduction)

Pourquoi avons-nous besoin d’une liste chaînée déroulée ?

One of the biggest advantages of linked lists over arrays is that inserting an element at any location takes only O(1). However the catch here is that to search an element in a linked list takes O(n). So to solve the problem of searching i.e reducing the time for searching the element the concept of unrolled linked lists was put forward. La liste chaînée déroulée couvre les avantages à la fois du tableau et de la liste chaînée car elle réduit la surcharge de mémoire par rapport aux listes chaînées simples en stockant plusieurs éléments sur chaque nœud et elle présente également l'avantage d'une insertion et d'une suppression rapides comme celle d'une liste chaînée.

Liste chaînée déroulée | Ensemble 1 (Introduction) liste liée déroulée

Avantages :

  • En raison du comportement du cache, la recherche linéaire est beaucoup plus rapide dans les listes chaînées déroulées.
  • Il effectue des opérations telles que la suppression d'insertion et le parcours plus rapidement que les listes chaînées ordinaires (car la recherche est plus rapide).

Inconvénients :

  • The overhead per node is comparatively high than singly-linked lists. Reportez-vous à un exemple de nœud dans le code ci-dessous

Exemple: Let say we are having 8 elements so sqrt(8)=2.82 which rounds off to 3. So each block will store 3 elements. Par conséquent, pour stocker 8 éléments, 3 blocs seront créés, à partir desquels les deux premiers blocs stockeront 3 éléments et le dernier bloc stockera 2 éléments.

Comment la recherche devient-elle meilleure dans les listes chaînées déroulées ?

Donc, en prenant l'exemple ci-dessus, si nous voulons rechercher le 7ème élément de la liste, nous parcourons la liste des blocs jusqu'à celui qui contient le 7ème élément. It takes only O(sqrt(n)) since we found it through not going more than sqrt(n) blocks. 

Mise en œuvre simple :

Le programme ci-dessous crée une simple liste chaînée déroulée avec 3 nœuds contenant un nombre variable d'éléments dans chacun. Il parcourt également la liste créée.

C++
   // C++ program to implement unrolled linked list    // and traversing it.    #include          using     namespace     std  ;   #define maxElements 4    // Unrolled Linked List Node    class     Node      {         public  :      int     numElements  ;         int     array  [  maxElements  ];         Node     *  next  ;      };      /* Function to traverse an unrolled linked list    and print all the elements*/   void     printUnrolledList  (  Node     *  n  )      {         while     (  n     !=     NULL  )         {         // Print elements in current node       for     (  int     i  =  0  ;     i   <  n  ->  numElements  ;     i  ++  )         cout   < <  n  ->  array  [  i  ]   < <  ' '  ;         // Move to next node       n     =     n  ->  next  ;         }      }      // Program to create an unrolled linked list    // with 3 Nodes    int     main  ()      {         Node  *     head     =     NULL  ;         Node  *     second     =     NULL  ;         Node  *     third     =     NULL  ;         // allocate 3 Nodes       head     =     new     Node  ();      second     =     new     Node  ();      third     =     new     Node  ();      // Let us put some values in second node (Number       // of values must be less than or equal to       // maxElement)       head  ->  numElements     =     3  ;         head  ->  array  [  0  ]     =     1  ;         head  ->  array  [  1  ]     =     2  ;         head  ->  array  [  2  ]     =     3  ;         // Link first Node with the second Node       head  ->  next     =     second  ;         // Let us put some values in second node (Number       // of values must be less than or equal to       // maxElement)       second  ->  numElements     =     3  ;         second  ->  array  [  0  ]     =     4  ;         second  ->  array  [  1  ]     =     5  ;         second  ->  array  [  2  ]     =     6  ;         // Link second Node with the third Node       second  ->  next     =     third  ;         // Let us put some values in third node (Number       // of values must be less than or equal to       // maxElement)       third  ->  numElements     =     3  ;         third  ->  array  [  0  ]     =     7  ;         third  ->  array  [  1  ]     =     8  ;         third  ->  array  [  2  ]     =     9  ;         third  ->  next     =     NULL  ;         printUnrolledList  (  head  );         return     0  ;      }      // This is code is contributed by rathbhupendra   
C
   // C program to implement unrolled linked list   // and traversing it.   #include      #include      #define maxElements 4   // Unrolled Linked List Node   struct     Node   {      int     numElements  ;      int     array  [  maxElements  ];      struct     Node     *  next  ;   };   /* Function to traverse an unrolled linked list    and print all the elements*/   void     printUnrolledList  (  struct     Node     *  n  )   {      while     (  n     !=     NULL  )      {      // Print elements in current node      for     (  int     i  =  0  ;     i   <  n  ->  numElements  ;     i  ++  )      printf  (  '%d '       n  ->  array  [  i  ]);      // Move to next node       n     =     n  ->  next  ;      }   }   // Program to create an unrolled linked list   // with 3 Nodes   int     main  ()   {      struct     Node  *     head     =     NULL  ;      struct     Node  *     second     =     NULL  ;      struct     Node  *     third     =     NULL  ;      // allocate 3 Nodes      head     =     (  struct     Node  *  )  malloc  (  sizeof  (  struct     Node  ));      second     =     (  struct     Node  *  )  malloc  (  sizeof  (  struct     Node  ));      third     =     (  struct     Node  *  )  malloc  (  sizeof  (  struct     Node  ));      // Let us put some values in second node (Number      // of values must be less than or equal to      // maxElement)      head  ->  numElements     =     3  ;      head  ->  array  [  0  ]     =     1  ;      head  ->  array  [  1  ]     =     2  ;      head  ->  array  [  2  ]     =     3  ;      // Link first Node with the second Node      head  ->  next     =     second  ;      // Let us put some values in second node (Number      // of values must be less than or equal to      // maxElement)      second  ->  numElements     =     3  ;      second  ->  array  [  0  ]     =     4  ;      second  ->  array  [  1  ]     =     5  ;      second  ->  array  [  2  ]     =     6  ;      // Link second Node with the third Node      second  ->  next     =     third  ;      // Let us put some values in third node (Number      // of values must be less than or equal to      // maxElement)      third  ->  numElements     =     3  ;      third  ->  array  [  0  ]     =     7  ;      third  ->  array  [  1  ]     =     8  ;      third  ->  array  [  2  ]     =     9  ;      third  ->  next     =     NULL  ;      printUnrolledList  (  head  );      return     0  ;   }   
Java
   // Java program to implement unrolled   // linked list and traversing it.    import     java.util.*  ;   class   GFG  {       static     final     int     maxElements     =     4  ;   // Unrolled Linked List Node    static     class   Node      {         int     numElements  ;         int     []  array     =     new     int  [  maxElements  ]  ;         Node     next  ;      };      // Function to traverse an unrolled    // linked list and print all the elements   static     void     printUnrolledList  (  Node     n  )      {         while     (  n     !=     null  )         {             // Print elements in current node       for  (  int     i     =     0  ;     i      <     n  .  numElements  ;     i  ++  )         System  .  out  .  print  (  n  .  array  [  i  ]     +     ' '  );         // Move to next node       n     =     n  .  next  ;         }      }      // Program to create an unrolled linked list    // with 3 Nodes    public     static     void     main  (  String  []     args  )      {         Node     head     =     null  ;         Node     second     =     null  ;         Node     third     =     null  ;         // Allocate 3 Nodes       head     =     new     Node  ();      second     =     new     Node  ();      third     =     new     Node  ();      // Let us put some values in second       // node (Number of values must be       // less than or equal to maxElement)       head  .  numElements     =     3  ;         head  .  array  [  0  ]     =     1  ;         head  .  array  [  1  ]     =     2  ;         head  .  array  [  2  ]     =     3  ;         // Link first Node with the       // second Node       head  .  next     =     second  ;         // Let us put some values in       // second node (Number of values      // must be less than or equal to       // maxElement)       second  .  numElements     =     3  ;         second  .  array  [  0  ]     =     4  ;         second  .  array  [  1  ]     =     5  ;         second  .  array  [  2  ]     =     6  ;         // Link second Node with the third Node       second  .  next     =     third  ;         // Let us put some values in third       // node (Number of values must be      // less than or equal to maxElement)       third  .  numElements     =     3  ;         third  .  array  [  0  ]     =     7  ;         third  .  array  [  1  ]     =     8  ;         third  .  array  [  2  ]     =     9  ;         third  .  next     =     null  ;         printUnrolledList  (  head  );      }      }      // This code is contributed by amal kumar choubey    
Python3
   # Python3 program to implement unrolled   # linked list and traversing it.    maxElements   =   4   # Unrolled Linked List Node    class   Node  :   def   __init__  (  self  ):   self  .  numElements   =   0   self  .  array   =   [  0   for   i   in   range  (  maxElements  )]   self  .  next   =   None   # Function to traverse an unrolled linked list    # and print all the elements   def   printUnrolledList  (  n  ):   while   (  n   !=   None  ):   # Print elements in current node    for   i   in   range  (  n  .  numElements  ):   print  (  n  .  array  [  i  ]   end   =   ' '  )   # Move to next node    n   =   n  .  next   # Driver Code   if   __name__  ==  '__main__'  :   head   =   None   second   =   None   third   =   None   # Allocate 3 Nodes    head   =   Node  ()   second   =   Node  ()   third   =   Node  ()   # Let us put some values in second   # node (Number of values must be    # less than or equal to    # maxElement)    head  .  numElements   =   3   head  .  array  [  0  ]   =   1   head  .  array  [  1  ]   =   2   head  .  array  [  2  ]   =   3   # Link first Node with the second Node    head  .  next   =   second   # Let us put some values in second node   # (Number of values must be less than   # or equal to maxElement)    second  .  numElements   =   3   second  .  array  [  0  ]   =   4   second  .  array  [  1  ]   =   5   second  .  array  [  2  ]   =   6   # Link second Node with the third Node    second  .  next   =   third   # Let us put some values in third node   # (Number of values must be less than    # or equal to maxElement)    third  .  numElements   =   3   third  .  array  [  0  ]   =   7   third  .  array  [  1  ]   =   8   third  .  array  [  2  ]   =   9   third  .  next   =   None   printUnrolledList  (  head  )   # This code is contributed by rutvik_56   
C#
   // C# program to implement unrolled   // linked list and traversing it.    using     System  ;   class     GFG  {       static     readonly     int     maxElements     =     4  ;   // Unrolled Linked List Node    class     Node      {         public     int     numElements  ;         public     int     []  array     =     new     int  [  maxElements  ];         public     Node     next  ;      };      // Function to traverse an unrolled    // linked list and print all the elements   static     void     printUnrolledList  (  Node     n  )      {         while     (  n     !=     null  )         {         // Print elements in current node       for  (  int     i     =     0  ;     i      <     n  .  numElements  ;     i  ++  )         Console  .  Write  (  n  .  array  [  i  ]     +     ' '  );         // Move to next node       n     =     n  .  next  ;         }      }      // Program to create an unrolled linked list    // with 3 Nodes    public     static     void     Main  (  String  []     args  )      {         Node     head     =     null  ;         Node     second     =     null  ;         Node     third     =     null  ;         // Allocate 3 Nodes       head     =     new     Node  ();      second     =     new     Node  ();      third     =     new     Node  ();      // Let us put some values in second       // node (Number of values must be       // less than or equal to maxElement)       head  .  numElements     =     3  ;         head  .  array  [  0  ]     =     1  ;         head  .  array  [  1  ]     =     2  ;         head  .  array  [  2  ]     =     3  ;         // Link first Node with the       // second Node       head  .  next     =     second  ;         // Let us put some values in       // second node (Number of values      // must be less than or equal to       // maxElement)       second  .  numElements     =     3  ;         second  .  array  [  0  ]     =     4  ;         second  .  array  [  1  ]     =     5  ;         second  .  array  [  2  ]     =     6  ;         // Link second Node with the third Node       second  .  next     =     third  ;         // Let us put some values in third       // node (Number of values must be      // less than or equal to maxElement)       third  .  numElements     =     3  ;         third  .  array  [  0  ]     =     7  ;         third  .  array  [  1  ]     =     8  ;         third  .  array  [  2  ]     =     9  ;         third  .  next     =     null  ;         printUnrolledList  (  head  );      }      }      // This code is contributed by Rajput-Ji    
JavaScript
    <  script  >      // JavaScript program to implement unrolled      // linked list and traversing it.      const     maxElements     =     4  ;      // Unrolled Linked List Node      class     Node     {      constructor  ()     {      this  .  numElements     =     0  ;      this  .  array     =     new     Array  (  maxElements  );      this  .  next     =     null  ;      }      }      // Function to traverse an unrolled      // linked list and print all the elements      function     printUnrolledList  (  n  )     {      while     (  n     !=     null  )     {      // Print elements in current node      for     (  var     i     =     0  ;     i      <     n  .  numElements  ;     i  ++  )      document  .  write  (  n  .  array  [  i  ]     +     ' '  );      // Move to next node      n     =     n  .  next  ;      }      }      // Program to create an unrolled linked list      // with 3 Nodes      var     head     =     null  ;      var     second     =     null  ;      var     third     =     null  ;      // Allocate 3 Nodes      head     =     new     Node  ();      second     =     new     Node  ();      third     =     new     Node  ();      // Let us put some values in second      // node (Number of values must be      // less than or equal to maxElement)      head  .  numElements     =     3  ;      head  .  array  [  0  ]     =     1  ;      head  .  array  [  1  ]     =     2  ;      head  .  array  [  2  ]     =     3  ;      // Link first Node with the      // second Node      head  .  next     =     second  ;      // Let us put some values in      // second node (Number of values      // must be less than or equal to      // maxElement)      second  .  numElements     =     3  ;      second  .  array  [  0  ]     =     4  ;      second  .  array  [  1  ]     =     5  ;      second  .  array  [  2  ]     =     6  ;      // Link second Node with the third Node      second  .  next     =     third  ;      // Let us put some values in third      // node (Number of values must be      // less than or equal to maxElement)      third  .  numElements     =     3  ;      third  .  array  [  0  ]     =     7  ;      third  .  array  [  1  ]     =     8  ;      third  .  array  [  2  ]     =     9  ;      third  .  next     =     null  ;      printUnrolledList  (  head  );        <  /script>   

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Analyse de complexité :

    Complexité temporelle : O(n). Complexité spatiale : O(n).

Dans cet article, nous avons présenté une liste déroulée et ses avantages. Nous avons également montré comment parcourir la liste. Dans le prochain article, nous discuterons en détail de la suppression par insertion et des valeurs de maxElements/numElements.

Insertion dans une liste chaînée déroulée