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Here is the lecture on queues and linked lists by Prof Naveen Garg.

Learn Linked Lists in 10 minutes from the following video:

This video is also a very good source:

http://www.csanimated.com/animation.php?t=Linked_list

**1. Singly Linked List:**

A singly link list consists of one or more nodes with each node having a next pointer that points to the next node.

A very simple Node with all the operations might look like this in Python:

#node of a Singly Linked List class Node: #constructor def __init__(self): self.data = None self.next = None #method for setting the data field of the node def setData(self,data): self.data = data #method for getting the data field of the node def getData(self): return self.data #method for setting the next field of the node def setNext(self,next): self.next = next #method for getting the next field of the node def getNext(self): return self.next

Now that we have dealt with the nodes. Lets deal with the actual Linked List that contain these nodes.

The basic operations in a singly linked list are:

1. Traversing a Linked List

2. Inserting an element in the Linked List

3. Deleting an element in the Linked List

The code for implementing a Singly Linked List is as follows:

#A Singly Linked List class SinglyLinkedList: #constructor def __init__(self): self.head = None self.length = 0 #method for setting the head of the Linked List def setHead(self,head): self.head = head #method for inserting a new node at the beginning of the Linked List (at the head) def insertAtBeg(self,data): newNode = Node() newNode.setData(data) if self.length == 0: self.head = newNode else: newNode.setNext(self.head) self.head = newNode self.length += 1 #method for inserting a new node at the end of a Linked List def insertAtEnd(self,data): newNode = Node() newNode.setData(data) current = self.head while current.getNext() != None: current = current.getNext() current.setNext(newNode) self.length += 1 #method for inserting a new node at any position in a Linked List def insertAtPos(self,pos,data): if pos > self.length or pos < 0: return None else: if pos == 0: self.insertAtBeg(data) else: if pos == self.length: self.insertAtEnd(data) else: newNode = Node() newNode.setData(data) count = 0 current = self.head while count < pos-1: count += 1 current = current.getNext() newNode.setNext(current.getNext()) current.setNext(newNode) self.length += 1 #method for traversing and printing the Linked List def printList(self): current = self.head while current != None: print current.getData() current = current.getNext() #method for deleting a node having a certain data def delete(self,data): current = self.head previous = self.head if self.head.getData() == data: self.head = self.head.getNext() else: while (current.getData() != data): previous = current current = current.getNext() if current.getData() == data: previous.setNext(current.getNext()) else: return None if __name__ == "__main__": ll = SinglyLinkedList() ll.insertAtBeg(1) ll.insertAtBeg(2) ll.insertAtEnd(3) ll.insertAtPos(0, 4) ll.insertAtPos(4,5) ll.insertAtPos(2,9) ll.printList() ll.delete(9) print "Linked List After Deletion" ll.printList() print "Deleting the last element" ll.delete(5) ll.printList()

**2. Doubly Linked List**

A node in a doubly linked list can be defined using a class. It might look as follows:

class Node: #constructor def __init__(self): self.data = 0 self.next = None self.previous = None #method for setting the value of a node def setValue(self,value): self.data = value #method for getting the value of a node def getValue(self): return self.data #method for setting the next node of a node def setNext(self,next): self.next = next #method for getting the next node of a node def getNext(self): return self.next #method for setting the previous node of a node def setPrevious(self,previous): self.previous = previous #method for getting the previous node of a node def getPrevious(self): return self.previous

The basic operations in a Doubly Linked List is again

1. Insertion

2. Deletion

3. Traversal

The class for Doubly Linked List along with its operations is defined as follows:

class DoublyLinkedList: #constructor def __init__(self): self.head = None #head of the list self.length = 0 #length of the list #method for inserting at the beginning of the list def insertAtBeg(self,value): newNode = Node() newNode.setValue(value) newNode.setNext(None) newNode.setPrevious(None) if self.length == 0: self.head = newNode self.length += 1 else: newNode.setNext(self.head) self.head.setPrevious(newNode) self.head = newNode self.length += 1 #method for inserting a node at the end def insertAtEnd(self,value): newNode = Node() newNode.setValue(value) current = self.head while(current.getNext() != None): current = current.getNext() newNode.setNext(current.getNext()) newNode.setPrevious(current) current.setNext(newNode) self.length += 1 #method for inserting a node at the middle def insertAtMid(self,pos,value): newNode = Node() newNode.setValue(value) current = self.head count = 0 while(count < pos-1): current = current.getNext() count += 1 current.getNext().setPrevious(newNode) newNode.setNext(current.getNext()) current.setNext(newNode) newNode.setPrevious(current) self.length += 1 #method for traversing and printing the list def printList(self): current = self.head while current != None: print current.getValue() current = current.getNext()

**3. Circular Linked List**

Here is a list of problems related to Linked Lists.

1. Find the nth node from the end of a singly linked list.

2. Write a program to implement ordered singly linked lists.

3. Write a program to detect a cycle in a linked list.