An unrolled linked list is a linked list of small arrays, all of the same size where each is so small that the insertion or deletion is fast and quick, but large enough to fill the cache line. An iterator pointing into the list consists of both a pointer to a node and an index into that node containing an array. It is also a data structure and is another variant of Linked List. It is related to B-Tree. It can store an array of elements at a node unlike a normal linked list which stores single element at a node. It is combination of arrays and linked list fusion-ed into one. It increases cache performance and decreases the memory overhead associated with storing reference for metadata. Other major advantages and disadvantages are already mentioned in the previous article.
Prerequisite : Introduction to Unrolled Linked List
Below is the insertion and display operation of Unrolled Linked List.
Input : 72 76 80 94 90 70 capacity = 3 Output : Unrolled Linked List : 72 76 80 94 90 70 Explanation : The working is well shown in the algorithm below. The nodes get broken at the mentioned capacity i.e., 3 here, when 3rd element is entered, the flow moves to another newly created node. Every node contains an array of size (int)[(capacity / 2) + 1]. Here it is 2. Input : 49 47 62 51 77 17 71 71 35 76 36 54 capacity = 5 Output : Unrolled Linked List : 49 47 62 51 77 17 71 71 35 76 36 54 Explanation : The working is well shown in the algorithm below. The nodes get broken at the mentioned capacity i.e., 5 here, when 5th element is entered, the flow moves to another newly created node. Every node contains an array of size (int)[(capacity / 2) + 1]. Here it is 3.
Algorithm :
Insert (ElementToBeInserted) if start_pos == NULL Insert the first element into the first node start_pos.numElement ++ end_pos = start_pos If end_pos.numElements + 1 < node_size end_pos.numElements.push(newElement) end_pos.numElements ++ else create a new Node new_node move final half of end_pos.data into new_node.data new_node.data.push(newElement) end_pos.numElements = end_pos.data.size / 2 + 1 end_pos.next = new_node end_pos = new_node
Implementation: Following is the Java implementation of the insertion and display operation. In the below code, the capacity is 5 and random numbers are input.
// C++ program to show the insertion operation of Unrolled Linked List #include <iostream> #include <cstdlib> #include <ctime> using namespace std;
// class for each node class UnrollNode {
public :
UnrollNode* next;
int num_elements;
int * array;
// Constructor
UnrollNode( int n)
{
next = nullptr;
num_elements = 0;
array = new int [n];
}
}; // Operation of Unrolled Function class UnrollLinkList {
private :
UnrollNode* start_pos;
UnrollNode* end_pos;
int size_node;
int nNode;
public :
// Parameterized Constructor
UnrollLinkList( int capacity)
{
start_pos = nullptr;
end_pos = nullptr;
nNode = 0;
size_node = capacity + 1;
}
// Insertion operation
void Insert( int num)
{
nNode++;
// Check if the list starts from NULL
if (start_pos == nullptr) {
start_pos = new UnrollNode(size_node);
start_pos->array[0] = num;
start_pos->num_elements++;
end_pos = start_pos;
return ;
}
// Attaching the elements into nodes
if (end_pos->num_elements + 1 < size_node) {
end_pos->array[end_pos->num_elements] = num;
end_pos->num_elements++;
}
// Creation of new Node
else {
UnrollNode* node_pointer = new UnrollNode(size_node);
int j = 0;
for ( int i = end_pos->num_elements / 2 + 1;
i < end_pos->num_elements; i++)
node_pointer->array[j++] = end_pos->array[i];
node_pointer->array[j++] = num;
node_pointer->num_elements = j;
end_pos->num_elements = end_pos->num_elements / 2 + 1;
end_pos->next = node_pointer;
end_pos = node_pointer;
}
}
// Display the Linked List
void display()
{
cout << "\nUnrolled Linked List = " << endl;
UnrollNode* pointer = start_pos;
while (pointer != nullptr) {
for ( int i = 0; i < pointer->num_elements; i++)
cout << pointer->array[i] << " " ;
cout << endl;
pointer = pointer->next;
}
cout << endl;
}
}; // Main Class int main()
{ srand ( time (0));
UnrollLinkList ull(5);
// Perform Insertion Operation
for ( int i = 0; i < 12; i++) {
// Generate random integers in range 0 to 99
int rand_int1 = rand () % 100;
cout << "Entered Element is " << rand_int1 << endl;
ull.Insert(rand_int1);
ull.display();
}
return 0;
} // This code is contributed by Vikram_Shirsat |
# Python program to show the insertion operation of Unrolled Linked List import random
# class for each node class UnrollNode:
def __init__( self , n):
self . next = None
self .num_elements = 0
self .array = [ 0 ] * n
# Operation of Unrolled Function class UnrollLinkList:
def __init__( self , capacity):
self .start_pos = None
self .end_pos = None
self .nNode = 0
self .size_node = capacity + 1
# Insertion operation
def Insert( self , num):
self .nNode + = 1
# Check if the list starts from NULL
if self .start_pos is None :
self .start_pos = UnrollNode( self .size_node)
self .start_pos.array[ 0 ] = num
self .start_pos.num_elements + = 1
self .end_pos = self .start_pos
return
# Attaching the elements into nodes
if self .end_pos.num_elements + 1 < self .size_node:
self .end_pos.array[ self .end_pos.num_elements] = num
self .end_pos.num_elements + = 1
# Creation of new Node
else :
node_pointer = UnrollNode( self .size_node)
j = 0
for i in range ( self .end_pos.num_elements / / 2 + 1 , self .end_pos.num_elements):
node_pointer.array[j] = self .end_pos.array[i]
j + = 1
node_pointer.array[j] = num
node_pointer.num_elements = j + 1
self .end_pos.num_elements = self .end_pos.num_elements / / 2 + 1
self .end_pos. next = node_pointer
self .end_pos = node_pointer
# Display the Linked List
def display( self ):
print ( "\nUnrolled Linked List = " )
pointer = self .start_pos
while pointer is not None :
for i in range (pointer.num_elements):
print (pointer.array[i], end = " " )
print ()
pointer = pointer. next
print ()
# Main function if __name__ = = "__main__" :
ull = UnrollLinkList( 5 )
# Perform Insertion Operation
for i in range ( 12 ):
# Generate random integers in range 0 to 99
rand_int1 = random.randint( 0 , 99 )
print ( "Entered Element is " , rand_int1)
ull.Insert(rand_int1)
ull.display()
# This code is contributed by Vikram_Shirsat |
/* C# program to show the insertion operation * of Unrolled Linked List */ using System;
// class for each node public class UnrollNode {
public UnrollNode next;
public int num_elements;
public int [] array;
// Constructor
public UnrollNode( int n)
{
next = null ;
num_elements = 0;
array = new int [n];
}
} // Operation of Unrolled Function public class UnrollLinkList {
private UnrollNode start_pos;
private UnrollNode end_pos;
int size_node;
int nNode;
// Parameterized Constructor
public UnrollLinkList( int capacity)
{
start_pos = null ;
end_pos = null ;
nNode = 0;
size_node = capacity + 1;
}
// Insertion operation
public void Insert( int num)
{
nNode++;
// Check if the list starts from NULL
if (start_pos == null ) {
start_pos = new UnrollNode(size_node);
start_pos.array[0] = num;
start_pos.num_elements++;
end_pos = start_pos;
return ;
}
// Attaching the elements into nodes
if (end_pos.num_elements + 1 < size_node) {
end_pos.array[end_pos.num_elements] = num;
end_pos.num_elements++;
}
// Creation of new Node
else {
UnrollNode node_pointer = new UnrollNode(size_node);
int j = 0;
for ( int i = end_pos.num_elements / 2 + 1;
i < end_pos.num_elements; i++)
node_pointer.array[j++] = end_pos.array[i];
node_pointer.array[j++] = num;
node_pointer.num_elements = j;
end_pos.num_elements = end_pos.num_elements / 2 + 1;
end_pos.next = node_pointer;
end_pos = node_pointer;
}
}
// Display the Linked List
public void display()
{
Console.Write( "\nUnrolled Linked List = " );
Console.WriteLine();
UnrollNode pointer = start_pos;
while (pointer != null ) {
for ( int i = 0; i < pointer.num_elements; i++)
Console.Write(pointer.array[i] + " " );
Console.WriteLine();
pointer = pointer.next;
}
Console.WriteLine();
}
} /* Main Class */ public class UnrolledLinkedList_Check {
// Driver code
public static void Main(String[] args)
{
// create instance of Random class
Random rand = new Random();
UnrollLinkList ull = new UnrollLinkList(5);
// Perform Insertion Operation
for ( int i = 0; i < 12; i++) {
// Generate random integers in range 0 to 99
int rand_int1 = rand.Next(100);
Console.WriteLine( "Entered Element is " + rand_int1);
ull.Insert(rand_int1);
ull.display();
}
}
} // This code has been contributed by 29AjayKumar |
/* Java program to show the insertion operation * of Unrolled Linked List */ import java.util.Scanner;
import java.util.Random;
// class for each node class UnrollNode {
UnrollNode next;
int num_elements;
int array[];
// Constructor
public UnrollNode( int n)
{
next = null ;
num_elements = 0 ;
array = new int [n];
}
} // Operation of Unrolled Function class UnrollLinkList {
private UnrollNode start_pos;
private UnrollNode end_pos;
int size_node;
int nNode;
// Parameterized Constructor
UnrollLinkList( int capacity)
{
start_pos = null ;
end_pos = null ;
nNode = 0 ;
size_node = capacity + 1 ;
}
// Insertion operation
void Insert( int num)
{
nNode++;
// Check if the list starts from NULL
if (start_pos == null ) {
start_pos = new UnrollNode(size_node);
start_pos.array[ 0 ] = num;
start_pos.num_elements++;
end_pos = start_pos;
return ;
}
// Attaching the elements into nodes
if (end_pos.num_elements + 1 < size_node) {
end_pos.array[end_pos.num_elements] = num;
end_pos.num_elements++;
}
// Creation of new Node
else {
UnrollNode node_pointer = new UnrollNode(size_node);
int j = 0 ;
for ( int i = end_pos.num_elements / 2 + 1 ;
i < end_pos.num_elements; i++)
node_pointer.array[j++] = end_pos.array[i];
node_pointer.array[j++] = num;
node_pointer.num_elements = j;
end_pos.num_elements = end_pos.num_elements / 2 + 1 ;
end_pos.next = node_pointer;
end_pos = node_pointer;
}
}
// Display the Linked List
void display()
{
System.out.print( "\nUnrolled Linked List = " );
System.out.println();
UnrollNode pointer = start_pos;
while (pointer != null ) {
for ( int i = 0 ; i < pointer.num_elements; i++)
System.out.print(pointer.array[i] + " " );
System.out.println();
pointer = pointer.next;
}
System.out.println();
}
} /* Main Class */ class UnrolledLinkedList_Check {
// Driver code
public static void main(String args[])
{
Scanner sc = new Scanner(System.in);
// create instance of Random class
Random rand = new Random();
UnrollLinkList ull = new UnrollLinkList( 5 );
// Perform Insertion Operation
for ( int i = 0 ; i < 12 ; i++) {
// Generate random integers in range 0 to 99
int rand_int1 = rand.nextInt( 100 );
System.out.println( "Entered Element is " + rand_int1);
ull.Insert(rand_int1);
ull.display();
}
}
} |
<script> /* Javascript program to show the insertion operation * of Unrolled Linked List */ // class for each node class UnrollNode { // Constructor
constructor(n)
{
this .next = null ;
this .num_elements = 0;
this .array = new Array(n);
for (let i = 0; i < n; i++)
{
this .array[i] = 0;
}
}
} // Operation of Unrolled Function class UnrollLinkList { // Parameterized Constructor
constructor(capacity)
{
this .start_pos = null ;
this .end_pos = null ;
this .nNode = 0;
this .size_node = capacity + 1;
}
// Insertion operation
Insert(num)
{
this .nNode++;
// Check if the list starts from NULL
if ( this .start_pos == null ) {
this .start_pos = new UnrollNode( this .size_node);
this .start_pos.array[0] = num;
this .start_pos.num_elements++;
this .end_pos = this .start_pos;
return ;
}
// Attaching the elements into nodes
if ( this .end_pos.num_elements + 1 < this .size_node) {
this .end_pos.array[ this .end_pos.num_elements] = num;
this .end_pos.num_elements++;
}
// Creation of new Node
else {
let node_pointer = new UnrollNode( this .size_node);
let j = 0;
for (let i = Math.floor( this .end_pos.num_elements / 2 )+ 1;
i < this .end_pos.num_elements; i++)
node_pointer.array[j++] = this .end_pos.array[i];
node_pointer.array[j++] = num;
node_pointer.num_elements = j;
this .end_pos.num_elements = Math.floor( this .end_pos.num_elements / 2) + 1;
this .end_pos.next = node_pointer;
this .end_pos = node_pointer;
}
}
// Display the Linked List
display()
{
document.write( "<br>Unrolled Linked List = " );
document.write( "<br>" );
let pointer = this .start_pos;
while (pointer != null ) {
for (let i = 0; i < pointer.num_elements; i++)
document.write(pointer.array[i] + " " );
document.write( "<br>" );
pointer = pointer.next;
}
document.write( "<br>" );
}
} // Driver code let ull = new UnrollLinkList(5);
// Perform Insertion Operation
for (let i = 0; i < 12; i++)
{ // Generate random integers in range 0 to 99
let rand_int1 = Math.floor(Math.random()*(100));
document.write( "Entered Element is " + rand_int1+ "<br>" );
ull.Insert(rand_int1);
ull.display();
} // This code is contributed by rag2127 </script> |
Entered Element is 67 Unrolled Linked List = 67 Entered Element is 69 Unrolled Linked List = 67 69 Entered Element is 50 Unrolled Linked List = 67 69 50 Entered Element is 60 Unrolled Linked List = 67 69 50 60 Entered Element is 18 Unrolled Linked List = 67 69 50 60 18 Entered Element is 15 Unrolled Linked List = 67 69 50 60 18 15 Entered Element is 41 Unrolled Linked List = 67 69 50 60 18 15 41 Entered Element is 79 Unrolled Linked List = 67 69 50 60 18 15 41 79 Entered Element is 12 Unrolled Linked List = 67 69 50 60 18 15 41 79 12 Entered Element is 95 Unrolled Linked List = 67 69 50 60 18 15 41 79 12 95 Entered Element is 37 Unrolled Linked List = 67 69 50 60 18 15 41 79 12 95 37 Entered Element is 13 Unrolled Linked List = 67 69 50 60 18 15 41 79 12 95 37 13
Time complexity : O(n)
Also, few real-world applications :
- It is used in B-Tree and T-Tree
- Used in Hashed Array Tree
- Used in Skip List
- Used in CDR Coding