Data Structures Quiz

Question 1

What is the average-case time complexity of a lookup in a hash table?

Accepted Answer

O(1)

Answer

O(log n)

Answer

O(n)

Answer

O(n log n)

Question 2

Which data structure follows Last-In-First-Out (LIFO)?

Accepted Answer

Stack

Answer

Queue

Answer

Linked list

Answer

Heap

Question 3

What is the time complexity of binary search on a sorted array of n elements?

Accepted Answer

O(log n)

Answer

O(1)

Answer

O(n)

Answer

O(n log n)

Question 4

Accessing an element by index in an array is…

Accepted Answer

O(1)

Answer

O(log n)

Answer

O(n)

Answer

O(n²)

Question 5

What is the main advantage of a linked list over an array?

Accepted Answer

O(1) insertion/deletion at a known position without shifting

Answer

Faster random access

Answer

Better cache locality

Answer

Less memory usage

Question 6

A max-heap guarantees that…

Accepted Answer

Each parent is greater than or equal to its children

Answer

The tree is fully sorted

Answer

It is a binary search tree

Answer

All leaves are at the same depth

Question 7

What is the worst-case time to search a balanced binary search tree?

Accepted Answer

O(log n)

Answer

O(1)

Answer

O(n)

Answer

O(n log n)

Question 8

Which structure is best for implementing a breadth-first search (BFS)?

Accepted Answer

Queue

Answer

Stack

Answer

Priority queue

Answer

Hash set only

Question 9

What does "amortized O(1)" mean for a dynamic array append?

Accepted Answer

Appends are O(1) on average across many operations, despite occasional O(n) resizes

Answer

Every single append is exactly O(1)

Answer

Appends are always O(n)

Answer

It only applies to linked lists

Question 10

A collision in a hash table is resolved by chaining using…

Accepted Answer

A linked list of entries per bucket

Answer

A second hash table

Answer

Binary search

Answer

Recomputing all hashes

Data Structures quiz

What is the average-case time complexity of a lookup in a hash table?

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