Question

Python 3:

Write a LinkedList method named contains, that takes a value as a parameter and returns True if that value is in the linked list, but returns False otherwise.

class Node:
    """
    Represents a node in a linked list
    """
    def __init__(self, data):
        self.data = data
        self.next = None

class LinkedList:
    """
    A linked list implementation of the List ADT
    """
    def __init__(self):
        self.head = None

    def add(self, val):
        """
        Adds a node containing val to the linked list
        """
        if self.head is None:  # If the list is empty
            self.head = Node(val)
        else:
            current = self.head
            while current.next is not None:
                current = current.next
            current.next = Node(val)

    def display(self):
        """
        Prints out the values in the linked list
        """
        current = self.head
        while current is not None:
            print(current.data, end=" ")
            current = current.next
        print()

    def remove(self, val):
        """
        Removes the node containing val from the linked list
        """
        if self.head is None:  # If the list is empty
            return

        if self.head.data == val:  # If the node to remove is the head
            self.head = self.head.next
        else:
            current = self.head
            while current is not None and current.data != val:
                previous = current
                current = current.next
            if current is not None:  # If we found the value in the list
                previous.next = current.next

    def is_empty(self):
        """
        Returns True if the linked list is empty,
        returns False otherwise
        """
        return self.head is None

Answer 1

THE METHOD CONTAINS IS BELOW WHICH WILL TAKE A ARGUMENT AND WILL RETURN TRUE IF THAT ELEMENT IS PRESENT IN THE LINK LIST AND FALSE IF NOT PRESENT.

def contains(self, item):  # contains method
    current = self.head   # here I have taken the head of the linklist and saved it to current 
    while current is not None:  # and iterated till the head is not empty
        if current.data == item:  # checking if the present node data is equal to the parameter
            return True   # if found returning true
        current = current.next  # else changing the node to the next node
    return False  # if after iterating the whole linklist, the element is not matched then returning false

THE WHOLE CODE WITH CONTAINS IS BELOW WITH OUTPUT:-

THE OUTPUT IS BELOW:-

THANK YOU