3-Module_2 Linked List - notes-02-08-2024 (1).pdf

Module 2 Topics : Linked List - Singly Linked List - Doubly Linked List - Circular Singly Linked List - Linked representation of Stack and Queue - Applications of Linked List Module 2 1. Linked List 2. Singly Linked List 3. Doubly Linked List 4....

Module 2 Topics : Linked List - Singly Linked List - Doubly Linked List - Circular Singly Linked List - Linked representation of Stack and Queue - Applications of Linked List Module 2 1. Linked List 2. Singly Linked List 3. Doubly Linked List 4. Circular Singly Linked List 5. Linked representation of Stack and Queue 6. Applications of Linked List Linked list A linked list is a data structure used to store a collection of elements. Unlike arrays, which store elements in contiguous memory locations, linked lists use nodes that are scattered throughout the memory, with each node pointing to the next one in the sequence. This flexibility allows for efficient insertion and deletion operation Node: The basic building block of a linked list. Each node contains: Data: The value or information stored in the node. Pointer/Reference: A reference to the next node in the list. Head: A pointer/reference to the first node in the linked list. It serves as the entry point for accessing the list. Node in a linked list A Node in linked list represents a single node. It typically contains two main components: the value or data stored in the node and a reference (or link) to the next node in the list. By connecting these nodes, we can create a flexible and efficient data structure capable of handling various operations. Module 2 1. Linked List 2. Singly Linked List 3. Doubly Linked List 4. Circular Singly Linked List 5. Linked representation of Stack and Queue 6. Applications of Linked List A singly linked list Head Types of linked lists and representation Singly linked list Doubly linked list Circular linked list Linked list representations: Array Stack Advantages &Disadvantages Advantages Dynamic Size: Can easily grow and shrink in size by adding or removing nodes. Efficient Insertions/Deletions: Adding or removing elements doesn’t require shifting elements, unlike arrays. Disadvantages Memory Overhead: Requires extra memory for storing pointers. No Random Access: Traversal is required to access an element at a specific position, making it less efficient for random access compared to arrays. Module 2 1. Linked List 2. Singly Linked List 3. Doubly Linked List 4. Circular Singly Linked List 5. Linked representation of Stack and Queue 6. Applications of Linked List Singly Linked List Single linked list is a sequence of elements in which every element has link to its next element in the sequence. In any single linked list, the individual element is called as "Node". Every "Node" contains two fields, data field, and the next field. The data field is used to store actual value of the node and next field is used to store the address of next node in the sequence. The graphical representation of a node in a single linked list is as follows... Node structure struct Node { int data; Node* next; };  Importent Points to be Remembered In a single linked list, the address of the first node is always stored in a reference node known as "front" (Some times it is also known as "head"). Always next part (reference part) of the last node must be NULL. Operations on Singly Linked List The following operations are performed on a Single Linked List Insertion Deletion Display Insertion In a singly linked list, the insertion operation can be performed in three ways. They are as follows... Inserting at the Beginning of the list Inserting at the End of the list Inserting at a Specific location in the list Inserting at the Beginning of the list We can use the following steps to insert a new node at beginning of the single linked list... Step 1 - Create a newNode with given value. Step 2 - Check whether list is Empty (head == NULL) Step 3 - If it is Empty then, set newNode→next = NULL and head = newNode. Step 4 - If it is Not Empty then, set newNode→next = head and head = newNode. Inserting at the End of the list We can use the following steps to insert a new node at end of the single linked list... Step 1 - Create a newNode with given value and newNode → next as NULL. Step 2 - Check whether list is Empty (head == NULL). Step 3 - If it is Empty then set head = newNode. Step 4 - If it is Not Empty then define a node pointer temp and initialize with head. Step 5 - Keep moving the temp to its next node until it reaches to the last node in the list (until temp → next is equal to NULL). Step 6 - Set temp → next = newNode. Inserting at a Specific location in the list (After a Node) We can use the following steps to insert a new node after a node in the single linked list... Step 1 - Create a newNode with given value. Step 2 - Check whether list is Empty (head == NULL) Step 3 - If it is Empty then, set newNode → next = NULL and head = newNode. Step 4 - If it is Not Empty then, define a node pointer temp and initialize with head. Step 5 - Keep moving the temp to its next node until it reaches to the node after which we want to insert the newNode (until temp1 → data is equal to location, here location is the node value after which we want to insert the newNode). Step 6 - Every time check whether temp is reached to last node or not. If it is reached to last node then display 'Given node is not found in the list!!! Insertion not possible!!!' and terminate the function. Otherwise move the temp to next node. Step 7 - Finally, Set 'newNode → next = temp → next' and 'temp → next = newNode' Deletion In a single linked list, the deletion operation can be performed in three ways. They are as follows... 1.Deletion at the Beginning of the list 2.Deletion at the End of the list 3.Deleting a Specific Node Deletion at the Beginning of the list Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty then, display 'List is Empty!!! Deletion is not possible' and terminate the function. Step 3 - If it is Not Empty then, define a Node pointer 'temp' and initialize with head. Step 4 - Check whether list is having only one node (temp → next == NULL) Step 5 - If it is TRUE then set head = NULL and delete temp (Setting Empty list conditions) Step 6 - If it is FALSE then set head = temp → next, and delete temp Deletion at the End of the list Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty then, display 'List is Empty!!! Deletion is not possible' and terminate the function. Step 3 - If it is Not Empty then, define two Node pointers 'temp1' and 'temp2' and initialize 'temp1' with head. Step 4 - Check whether list has only one Node (temp1 → next == NULL) Step 5 - If it is TRUE. Then, set head = NULL and delete temp1. And terminate the function. (Setting Empty list condition) Step 6 - If it is FALSE. Then, set 'temp2 = temp1 ' and move temp1 to its next node. Repeat the same until it reaches to the last node in the list. (until temp1 → next == NULL) Step 7 - Finally, Set temp2 → next = NULL and delete temp1. Deleting a Specific Node from the list Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty then, display 'List is Empty!!! Deletion is not possible' and terminate the function. Step 3 - If it is Not Empty then, define two Node pointers 'temp1' and 'temp2' and initialize 'temp1' with head. Step 4 - Keep moving the temp1 until it reaches to the exact node to be deleted or to the last node. And every time set 'temp2 = temp1' before moving the 'temp1' to its next node. Step 5 - If it is reached to the last node then display 'Given node not found in the list! Deletion not possible!!!'. And terminate the function. Step 6 - If it is reached to the exact node which we want to delete, then check whether list is having only one node or not Step 7 - If list has only one node and that is the node to be deleted, then set head = NULL and delete temp1 (free(temp1)). Step 8 - If list contains multiple nodes, then check whether temp1 is the first node in the list (temp1 == head). Step 9 - If temp1 is the first node then move the head to the next node (head = head → next) and delete temp1. Step 10 - If temp1 is not first node then check whether it is last node in the list (temp1 → next == NULL). Step 11 - If temp1 is last node then set temp2 → next = NULL and delete temp1 (free(temp1)). Step 12 - If temp1 is not first node and not last node then set temp2 → next = temp1 → next and delete temp1 (free(temp1)). Displaying a Single Linked List Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty then, display 'List is Empty!!!' and terminate the function. Step 3 - If it is Not Empty then, define a Node pointer 'temp' and initialize with head. Step 4 - Keep displaying temp → data with an arrow (--->) until temp reaches to the last node Step 5 - Finally display temp → data with arrow pointing to NULL (temp → data ---> NULL). Module 2 1. Linked List 2. Singly Linked List 3. Doubly Linked List 4. Circular Singly Linked List 5. Linked representation of Stack and Queue 6. Applications of Linked List Doubly linked list Doubly linked list is a sequence of elements in which every element has links to its previous element and next element in the sequence. A doubly linked list is a type of linked list in which each node consists of 3 components: *prev - address of the previous node data - data item *next - address of next node Important Points to be Remembered In double linked list, the first node must be always pointed by head. Always the previous field of the first node must be NULL. Always the next field of the last node must be NULL. Operations on Double Linked List In a double linked list, we perform the following operations... Insertion Deletion Display Insertion In a double linked list, the insertion operation can be performed in three ways as follows... Inserting At Beginning of the list Inserting At End of the list Inserting At Specific location in the list Inserting At Beginning of the list Step 1 - Create a newNode with given value and newNode → previous as NULL. Step 2 - Check whether list is Empty (head == NULL) Step 3 - If it is Empty then, assign NULL to newNode → next and newNode to head. Step 4 - If it is not Empty then, assign head to newNode → next and newNode to head. Inserting At End of the list Step 1 - Create a newNode with given value and newNode → next as NULL. Step 2 - Check whether list is Empty (head == NULL) Step 3 - If it is Empty, then assign NULL to newNode → previous and newNode to head. Step 4 - If it is not Empty, then, define a node pointer temp and initialize with head. Step 5 - Keep moving the temp to its next node until it reaches to the last node in the list (until temp → next is equal to NULL). Step 6 - Assign newNode to temp → next and temp to newNode → previous. Inserting At Specific location in the list (After a Node) Step 1 - Create a newNode with given value. Step 2 - Check whether list is Empty (head == NULL) Step 3 - If it is Empty then, assign NULL to both newNode → previous & newNode → next and set newNode to head. Step 4 - If it is not Empty then, define two node pointers temp1 & temp2 and initialize temp1 with head. Step 5 - Keep moving the temp1 to its next node until it reaches to the node after which we want to insert the newNode (until temp1 → data is equal to location, here location is the node value after which we want to insert the newNode). Step 6 - Every time check whether temp1 is reached to the last node. If it is reached to the last node then display 'Given node is not found in the list!!! Insertion not possible!!!' and terminate the function. Otherwise move the temp1 to next node. Step 7 - Assign temp1 → next to temp2, newNode to temp1 → next, temp1 to newNode → previous, temp2 to newNode → next and newNode to temp2 → previous. Deletion In a double linked list, the deletion operation can be performed in three ways as follows... Deleting from Beginning of the list Deleting from End of the list Deleting a Specific Node Deleting from Beginning of the list Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty then, display 'List is Empty!!! Deletion is not possible' and terminate the function. Step 3 - If it is not Empty then, define a Node pointer 'temp' and initialize with head. Step 4 - Check whether list is having only one node (temp → previous is equal to temp → next) Step 5 - If it is TRUE, then set head to NULL and delete temp (Setting Empty list conditions) Step 6 - If it is FALSE, then assign temp → next to head, NULL to head → previous and delete temp. Deleting from End of the list Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty, then display 'List is Empty!!! Deletion is not possible' and terminate the function. Step 3 - If it is not Empty then, define a Node pointer 'temp' and initialize with head. Step 4 - Check whether list has only one Node (temp → previous and temp → next both are NULL) Step 5 - If it is TRUE, then assign NULL to head and delete temp. And terminate from the function. (Setting Empty list condition) Step 6 - If it is FALSE, then keep moving temp until it reaches to the last node in the list. (until temp → next is equal to NULL) Step 7 - Assign NULL to temp → previous → next and delete temp. Deleting a Specific Node from the list Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty then, display 'List is Empty!!! Deletion is not possible' and terminate the function. Step 3 - If it is not Empty, then define a Node pointer 'temp' and initialize with head. Step 4 - Keep moving the temp until it reaches to the exact node to be deleted or to the last node. Step 5 - If it is reached to the last node, then display 'Given node not found in the list! Deletion not possible!!!' and terminate the fuction. Step 6 - If it is reached to the exact node which we want to delete, then check whether list is having only one node or not Step 7 - If list has only one node and that is the node which is to be deleted then set head to NULL and delete temp (free(temp)).  Step 8 - If list contains multiple nodes, then check whether temp is the first node in the list (temp == head). Step 9 - If temp is the first node, then move the head to the next node (head = head → next), set head of previous to NULL (head → previous = NULL) and delete temp. Step 10 - If temp is not the first node, then check whether it is the last node in the list (temp → next == NULL). Step 11 - If temp is the last node then set temp of previous of next to NULL (temp → previous → next = NULL) and delete temp (free(temp)). Step 12 - If temp is not the first node and not the last node, then set temp of previous of next to temp of next (temp → previous → next = temp → next), temp of next of previous to temp of previous (temp → next → previous = temp → previous) and delete temp (free(temp)). Displaying a Double Linked List Step 1 - Check whether list is Empty (head == NULL) Step 2 - If it is Empty, then display 'List is Empty!!!' and terminate the function. Step 3 - If it is not Empty, then define a Node pointer 'temp' and initialize with head. Step 4 - Display 'NULL