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- The textbook’s unordered list ADT uses a singly-linked list implementation. I added the _size and _tail attributes:
data next data next data next data next _head
_tail
_size 4
'w' 'a' 'y' 'c'
UnorderedList Object
a) The search(targetItem) method searches for targetItem in the list. It returns True if targetItem is in the list; otherwise it returns False. Complete the search(targetItem) method code:
class UnorderedList: def search(self, targetItem):
b) The textbook’s unordered list ADT does not allow duplicate items, so operations add(item), append(item), and insert(pos, item) would have what precondition?
c) Complete the append(item) method including a check of it’s precondition(s)?
def append(self, item):
d) Why do you suppose I added a _tail attribute?
Data Structures (CS 1520) Lecture 8 Name:_________________
Lecture 8 - Page 1
e) The textbook’s remove(item) and index(item) operations “Assume the item is present in the list.” Thus, they would have a precondition like “Item is in the list.” When writing a program using an UnorderedList object (say myGroceryList = UnorderedList() ), how would the programmer check if the precondition is satisfied? itemToRemove = input(“Enter the item to remove from the Grocery list: “)
if myGroceryList.remove(itemToRemove)
f) The remove(item) and index(item) methods both need to look for the item. What is inefficient in this whole process?
g) Modify the search(targetItem) method code in (a) to set additional data attributes to aid the implementation of the remove(item) and index(item) methods.
h) Write the index(item) method including a check of its precondition(s).
def index(self, item):
i) Write the remove(item) method including a check of its precondition(s).
def remove(self, item):
Data Structures (CS 1520) Lecture 8 Name:_________________
Lecture 8 - Page 2
