Hackerrank Python Data Structures & Algorithms 3

Question 1

What is the time complexity of inserting an element at the beginning of a Python list?

Accepted Answer

O(n)

Answer

O(1)

Answer

O(log n)

Answer

O(n log n)

Question 2

Which Python collection type uses a hash table internally and guarantees O(1) average-case lookup?

Accepted Answer

dict

Answer

list

Answer

tuple

Answer

deque

Question 3

What does `collections.deque` provide that a regular list does not?

Accepted Answer

O(1) appends and pops from both ends

Answer

Sorted order

Answer

Duplicate removal

Answer

Thread-safe reads

Question 4

Given `d = defaultdict(list)`, what happens when you access `d['new_key']`?

Accepted Answer

An empty list is created and returned

Answer

KeyError is raised

Answer

None is returned

Answer

0 is returned

Question 5

Which algorithm does Python's built-in `sort()` use?

Accepted Answer

Timsort

Answer

Quicksort

Answer

Heapsort

Answer

Mergesort

Question 6

What is the space complexity of a recursive Fibonacci function without memoization for input n?

Accepted Answer

O(n)

Answer

O(1)

Answer

O(2^n)

Answer

O(log n)

Question 7

Which data structure is most appropriate for implementing a LIFO (Last-In, First-Out) pattern in Python?

Accepted Answer

list used with append/pop

Answer

collections.deque used as a queue

Answer

heapq module

Answer

collections.OrderedDict