Array Deletion at End in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does 'Array Deletion at End' mean?

It means removing the last element from an array, making the array one element shorter.

beginner

What happens to the array size after deleting the last element?

The size of the array decreases by one because the last element is removed.

intermediate

Why is deleting the last element in an array efficient?

Because it does not require shifting any other elements, so it takes constant time (O(1)).

beginner

Show the Python code to delete the last element from a list named 'arr'.

Use arr.pop() to remove and return the last element from the list.

intermediate

What happens if you try to delete the last element from an empty array?

It causes an error because there is no element to remove.

What is the time complexity of deleting the last element from an array?

A O(log n)

B O(n)

C O(1)

D O(n^2)

Deleting the last element is done in constant time because no shifting is needed.

Which Python method removes the last element from a list?

A remove()

B pop()

C delete()

D discard()

pop() removes and returns the last element of the list.

What happens if you call pop() on an empty list in Python?

A Raises IndexError

B Removes first element

C Returns None

D Does nothing

pop() on an empty list raises an IndexError because there is no element to remove.

After deleting the last element, what is the new last element of the array?

A The first element

B No element

C The deleted element

D The element before the deleted one

The new last element is the one before the deleted last element.

Which of these is NOT a valid reason why deleting the last element is efficient?

A It requires scanning the whole array

B It takes constant time

C No elements need to be shifted

D It directly accesses the last element

Deleting the last element does NOT require scanning the whole array.

Explain how deleting the last element from an array works and why it is efficient.

Think about what happens to the array length and other elements.

Write a simple Python code snippet to delete the last element from a list and handle the case when the list is empty.

Use pop() inside a try block and catch IndexError.