Linked-List

Code For LinkedList and Different Operations on Them.

Method !

class Node: def init(self, data = None , next = None): self.data = data self.next = next

class LinkedList: def init(self): self.head = None

insert in Linked List

def insert_at_beginig(self, data):
    node = Node(data, self.head)
    self.head =node

Print linked list

def print(self):
    if self.head is None:
        print("empty")
        return
    itr = self.head
    llstr = ''

    while itr:
        llstr += str(itr.data) + '-->'
        itr = itr.next
    print(llstr)

Insert at the end of linked list

def insert_at_end(self,data):
    if self.head is None:
        self.head = Node(data, None)
        return

    itr = self.head
    while itr.next:
        itr = itr.next

    itr.next = Node(data,None) 

Inserting an Array

def inster_values(self , data_list):
    self.head = None
    for data in data_list:
        self.insert_at_end(data)

Length of the Inserted linked list

def get_length(self):
    count = 0
    itr = self.head
    while itr:
        count +=1
        itr = itr.next
    return count

Removing at Specific Index

def remove_at(self , index):
    if index<0 or index >= self.get_length():
        raise Exception("Invalid index")
    
    if index == 0:
        self.head = self.head.next
        return
    
    count = 0
    itr = self.head
    while itr:
        if count == index - 1:
            itr.next = itr.next.next
            break
        itr = itr.next
        count += 1

Inserting at given Index

def insert_at(self , index , data):
    if index<0 or index >= self.get_length():
        raise Exception("Invalid index")
    
    if index == 0:
        self.insert_at_beginig(data)
        return
    count = 0
    itr = self.head
    while itr:
        if count == index - 1:
            node = Node(data, itr.next)
            itr.next = node
        itr = itr.next
        count += 1

if name == 'main': ll = LinkedList() # ll.insert_at_beginig(5) # ll.insert_at_beginig(89) # ll.insert_at_end(79) ll.inster_values(['g','m','o' , 'p']) ll.remove_at(2) ll.print()

Method 2

linked list is a form of a sequential collection and it does not have to be in order. A linked list is made up of independent nodes that may contain any type of node that may contain any type of data and each node has a reference to the next node in the link.

A node store the refernece of the next node in the linked list so the tail has null reference .

types of linked list are 1 single linked list 2 circular linked list 3 double linked list 4 circular doubly linked list

class Node: def init(self, value=None): self.value = value self.next = None

class SLinkedList: def init(self): self.head = None self.tail = None def iter(self): node = self.head while node: yield node node = node.next

insert in Linked List

def insertSLL(self, value, location):
    newNode = Node(value)
    if self.head is None:
        self.head = newNode
        self.tail = newNode
    else:
        if location == 0:
            newNode.next = self.head
            self.head = newNode
        elif location == 1:
            newNode.next = None
            self.tail.next = newNode
            self.tail = newNode
        else:
            tempNode = self.head
            index = 0
            while index < location - 1:
                tempNode = tempNode.next
                index += 1
            nextNode = tempNode.next
            tempNode.next = newNode
            newNode.next = nextNode

Traverse Singly Linked List

def traverseList(self):
    if self.head is None:
        print("The Singly Linked List does not exist")
    else:
        node = self.head
        while node is not None:
            print(node.value)
            node = node.next

Search for a node in Singly Linked List

def searchSLL(self, nodeValue):
    if self.head is None:
        print("The Singly Linked List does not exist")
    else:
        node = self.head
        while node is not None:
            if node.value == nodeValue:
                return node.value
            node = node.next
        return "The node does not exist in this SLL"

Delete a node from Singly Linked List

def deleteNode(self, location):
    if self.head is None:
        return "The Singly Linked List does not exist"
    else:
        if location == 0:
            if self.head == self.tail:
                self.head = None
                self.tail = None
            else:
                self.head = self.head.next
        elif location == 1:
            if self.head == self.tail:
                self.head = None
                self.tail = None
            else:
                node = self.head
                while node is not None:
                    if node.next == self.tail:
                        break
                    node = node.next
                node.next = None
                self.tail = node
        else:
            tempNode = self.head
            index = 0
            while index < location-1:
                tempNode = tempNode.next
                index += 1
            nextNode = tempNode.next
            tempNode.next = nextNode.next

Delete entire SLL

def deleteEntireSLL(self):
    if self.head is None:
        print("SLL does not exist")
    else:
        self.head = None
        self.tail = None

singlyLinkedList = SLinkedList() singlyLinkedList.insertSLL(44,6) print([node.value for node in singlyLinkedList])

node1 = Node(1)

node2 = Node(2)

singlyLinkedList.head = node1

singlyLinkedList.head.next = node2

singlyLinkedList.tail = node2

singlyLinkedList.insertSLL(3,1) singlyLinkedList.insertSLL(4,1) print([node.value for node in singlyLinkedList]) singlyLinkedList.insertSLL(5,3) print([node.value for node in singlyLinkedList])

#for input in linked list

if inserstion at the begning of the list

1. node.next = head(head ka jo reference tha use node ka reference bana do) 2. head= node (head ke reference mai node ka(pointer) reference dal do)

if inserstion at the end of the list

node.next = null (list mai akhiri value ka refrence null hota hai) last.next = node (last element jo tha uske next yani refrence ko node ke reference ) tail = node (ab tail ko node se connect kr do refence daal kr)

if inserstion is in the middle of the linked list

find location(loop) 2. current.next = node( jo element find kra uske reference mai node ka reference daal do) 3 node.next = nextnode (node ke reference mai agle node ka reference daal do)