Traversal operations in LinkedList

Overview

A LinkedList is a collection of nodes that together represent a sequence.

It is a dynamic and linear data structure. It doesn’t need a contiguous memory location.
It can be visualized as a chain of nodes where each node contains a data field and a reference to the next node in the list.
LinkedList can be further classified into:

Singly LinkedList
Doubly LinkedList

What is `Traversal()`?

Traversal() is used to visit each node of the list to perform an operation. Here, we will traverse and print data present in the list.

Singly `LinkedList`

A singly LinkedList is Uni-directional, meaning traversal is possible in forwarding direction only.

Example

#Traversing using singly linked list
class Node:                   #Creating a node
    def __init__(self, data=None):
        self.data = data
        self.next = None
class SinglyLinkedList:           #Node is attribute of linkedlist
    def __init__(self):
        self.head = None
    def Traversal(self):   #Traversal through linked List
        n = self.head
        while n is not None:
            print (n.data)
            n = n.next
list = SinglyLinkedList()
list.head = Node("Monday")
l2 = Node("Tuesday")
l3 = Node("Wedneday")
# Link first Node to second node
list.head.next = l2
# Link second Node to third node
l2.next = l3
list.Traversal()

Explanation

Line 1–3: We initially create a node because a collection of nodes is a LinkedList.
Line 3–6: A node consists of two attributes, self.data = data and self.next = None.
Line 7–10: Next, we create a class named SinglyLinkedList.
Line 10–15: We use the Traversal() function to traverse along with the list.
Line 17–20: We are calling the list by assigning some values.
Line 20–26: For traversing further, it is important to link each node, which is done by list.head.next = l2 and l2.next = l3.

class Node:                     #Creating a node
    def __init__(self, data):
        self.data = data
        self.nref = None
        self.pref=None
class  doublyLinkedList:     #Node is attribute of linkedlist
    def __init__(self):
        self.head = None
    def insert_empty(self,data):
        if self.head is None:
            new_node=Node(data)
            self.head=new_node
    def add_begin(self,data):
      new_node=Node(data)
      if self.head is None:
          self.head=new_node
      else:
          new_node.nref=self.head
          self.head.pref=new_node
          self.head=new_node
    def add_end(self,data):
      new_node=Node(data)
      if self.head is None:
          self.head=new_node
      else:
        n=self.head
        while n.nref is not None:
             n=n.nref
        n.nref=new_node
        new_node.pref=n
       
    def Traversal_forward(self): #Traversal in forward direction 
        if self.head is None:
            print("Linked list is empty!")
        else:
             n=self.head
             while n is not None:
                 print(n.data)
                 n=n.nref
    def Traversal_backward(self):#Traversal in backward direction
        if self.head is None:
             print("LL is empty!")
        else:
             n=self.head
             while n.nref is not None:
                 n=n.nref
             while n is not None:
                print(n.data)
                n=n.pref    
dl1 = doublyLinkedList()
dl1.insert_empty('Monday')
dl1.add_begin('Tuesday')
dl1.Traversal_forward()   
dl1.Traversal_backward()

Explanation

Line 1–5: We create a node in doubly LinkedList. It consist of three attributes self.data = data, self.nref = None, and self.pref=None.
Line 6–10: We create a class doublyLinkedList() in which we can traverse in both directions.
Line 9–12: We use insert_empty() to insert elements in an empty LinkedList.
Line 13–20: We use add_begin() to add elements in the beginning, and change the self.head to the current node.
Line 20–25: We use add_end() to add elements in the end.
Line 20–30: We use Traversal_forward() and Traversal_backward() to traverse the LinkedList in both the directions.

In this way, traversal operation takes place in the LinkedList.

License: Creative Commons-Attribution-ShareAlike 4.0 (CC-BY-SA 4.0)

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Traversal operations in LinkedList

Overview

What is Traversal()?

Singly LinkedList

Example

Explanation

Doubly LinkedList

Example

Explanation

What is `Traversal()`?

Singly `LinkedList`

Doubly `LinkedList`