Chapter 3 1 Singly Linked List Data Structures

Chapter 3. 1 Singly Linked List Data Structures and Algorithms in Java

Objectives Discuss the following topics: • Motivation • What is Singly Linked List? • Singly Linked List Implementation – Insertion – Deletion – Searching Data Structures and Algorithms in Java 2

Motivation • Array is a very useful data structure, but it has at least two limitations: – (1) changing the size of the array requires creating a new array and then copying all data from the array with the old size to the new array – (2) the data in the array are next to each other sequentially in memory, which means inserting an item inside the array requires shifting some other data in this array. • This limitation can be overcome by using linked structures, the simplest of which is Linked List. Data Structures and Algorithms in Java 3

What is Singly Linked List? • A linked structure is a collection of nodes storing data and links to other nodes • A linked list is a data structure composed of list of nodes, each node holding some information and a reference to another node in the list • A singly linked list is a linked list in which each node has a link only to its successor in the list Data Structures and Algorithms in Java 4

What is Singly Linked List (continued) Figure 3. 1 A singly linked list Data Structures and Algorithms in Java 5

What is Singly Linked List (continued) Figure 3. 1 A singly linked list Data Structures and Algorithms in Java 6

What is Singly Linked List (continued) • Each node in the list in Figure 3. 1 is an instance of the following class definition: public class SLLNode<T> { public T info; public SLLNode<T> next; public SLLNode() { this(null, null); } public SLLNode(T el) { this(el, null); } public SLLNode(T el, SLLNode<T> ptr) { info = el; next = ptr; } } Data Structures and Algorithms in Java 7

What is Singly Linked List (continued) • One way of creating a Singly Linked List is to use its constructor. Example, the list in Fig 3. 1 can be created with the following statements: SLLNode<Integer> p = new SLLNode<Integer>(10); p. next = new SLLNode<Integer>(8); p. next = new SLLNode<Integer>(50); • Executing each statement above involves 4 steps as shown in Fig 3. 1 • Obviously, this method is not practical for longer lists. Data Structures and Algorithms in Java 8

Singly Linked List Implementation Figure 3. 2 An implementation of a generic singly linked list Data Structures and Algorithms in Java 9

Singly Linked List Implementation. . Figure 3 -2 (continued) Data Structures and Algorithms in Java 10

Singly Linked List Implementation. . Figure 3 -2 (continued) Data Structures and Algorithms in Java 11

Singly Linked List Implementation. . Data Structures and Algorithms in Java Figure 3 -2 (continued) 12

Singly Linked List Implementation. . Figure 3 -2 (continued) Data Structures and Algorithms in Java 13

Singly Linked List Implementation. . Figure 3 -2 (continued) Data Structures and Algorithms in Java 14

What is Singly Linked List (continued) • The singly linked list implementation in Figure 3. 2 uses two classes: – SLLNode, for nodes of the list, and – SLL, for managing the list. • SLL defines two data fields, head and tail, which are references to the first and the last nodes. • An example of a list is shown in Figure 3. 3. • The list is declared with the statement SLL<Integer> list = new SLL<Integer>(); Data Structures and Algorithms in Java 15

Singly Linked List Implementation. . Figure 3. 3 A singly linked list of integers • The first object in Figure 3. 3 a is not part of the list; it allows for having access to the list. • For simplicity, in subsequent figures, only nodes belonging to the list are shown. • The access node is omitted, and the head and tail fields are marked as in 3. 3(b) Data Structures and Algorithms in Java 16

Singly Linked List Implementation. . Figure 3. 4 Inserting a new node at the beginning of a singly linked list Data Structures and Algorithms in Java 17

Singly Linked List Implementation. . Figure 3. 5 Inserting a new node at the end of a singly linked list Data Structures and Algorithms in Java 18

Singly Linked List Implementation. . Figure 3. 6 Deleting a node from the beginning of a singly linked list Data Structures and Algorithms in Java 19

Singly Linked List Implementation. . Figure 3. 7 Deleting a node from the end of a singly linked list Data Structures and Algorithms in Java 20