CodeSignal Technical Assessment Data Structures

Question 1

What is the time complexity of accessing an element in an array by index?

Accepted Answer

O(1)

Answer

Array access by index is constant time because elements are stored in contiguous memory locations.

Question 2

What data structure uses FIFO (First In, First Out) ordering?

Accepted Answer

Queue

Answer

A queue processes elements in the order they arrive, like a line of people waiting.

Question 3

What is the time complexity of searching in a balanced binary search tree?

Accepted Answer

O(log n)

Answer

A balanced BST halves the search space at each comparison, giving logarithmic time complexity.

Question 4

What is a hash table collision?

Accepted Answer

When two different keys hash to the same index

Answer

Collisions occur when the hash function maps different keys to the same bucket, requiring resolution strategies like chaining or open addressing.

Question 5

What is the difference between a stack and a queue?

Accepted Answer

Stack uses LIFO (last in, first out); queue uses FIFO (first in, first out)

Answer

Stacks process the most recently added element first, while queues process the oldest element first.

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