CodeSignal Technical Assessment Coding Fundamentals 2

Question 1

What is the time complexity of accessing an element by index in a dynamic array (like Python's list)?

Accepted Answer

O(1)

Answer

Dynamic arrays store elements in contiguous memory, so index-based access is O(1) constant time.

Question 2

Which of the following correctly describes a stack data structure?

Accepted Answer

Last-In, First-Out (LIFO)

Answer

A stack follows LIFO: the last element pushed onto the stack is the first one popped off.

Question 3

Given the code snippet `x = [1, 2, 3]; y = x; y.append(4)`, what is the value of `x`?

Accepted Answer

[1, 2, 3, 4]

Answer

In Python, `y = x` creates a reference to the same list object, so mutating `y` also mutates `x`.

Question 4

What does a hash function guarantee when used in a hash table?

Accepted Answer

O(1) average-case lookup

Answer

Hash tables use a hash function to map keys to indices, providing O(1) average-case lookup time.

Question 5

In Python, what is the result of `bool([])` and `bool([0])`?

Accepted Answer

False, True

Answer

An empty list is falsy in Python, but a list containing any element (even 0) is truthy.

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