Data Structures and Algorithms Quiz

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

• O(1)

• O(n)

• O(log n)

• O(n²)

Which of the following is true about arrays in C/C++?

• Arrays can dynamically grow

• Indexing starts from 1

• Array size must be known at compile time

• Arrays are always initialized automatically

What will arr[5] return if arr has only 5 elements?

• The 5th element

• The 6th element

• Compilation error

• Runtime error only in C++

Which data structure is best for implementing multiple stacks in a single array?

• Queue

• Linked List

• Two pointer method

• Binary Tree

What’s the default garbage value in uninitialized array elements (in C++)?

• 0

• -1

• Random/Undefined

• NULL

Which is true about singly linked lists?

• Nodes have pointers to both previous and next

• Searching is O(1)

• Insertion at head is O(1)

• Memory is contiguous

What is stored in the last node of a singly linked list?

• Pointer to head

• NULL

• Next element

• Garbage

What’s the biggest drawback of singly linked lists?

• Too much memory

• No dynamic sizing

• No backward traversal

• Cannot insert in middle

Which is best suited for implementing undo functionality in apps?

• Queue

• Stack using linked list

• Array

• HashMap

Time complexity to delete the last node in singly linked list (without tail pointer)?

• O(1)

• O(n)

• O(log n)

• O(n²)