AMCAT Basic Data Structures 2

Question 1

Which operation on a singly linked list has O(n) time complexity in the worst case?

Accepted Answer

Accessing an element by index

Answer

Accessing by index requires traversing from the head, taking O(n) time in the worst case.

Question 2

What is the maximum number of elements that can be stored in a 2D array declared as int a[4][5]?

Accepted Answer

20

Answer

A 2D array of dimensions 4×5 holds 4*5 = 20 elements.

Question 3

In a doubly linked list, each node contains:

Accepted Answer

Data and two pointers (next and previous)

Answer

Each node in a doubly linked list stores data plus pointers to both the next and previous nodes.

Question 4

Which data structure uses a LIFO (Last In, First Out) access pattern?

Accepted Answer

Stack

Answer

A stack follows LIFO — the last element pushed is the first one popped.

Question 5

What is the time complexity for inserting an element at the beginning of a dynamic array (ArrayList)?

Accepted Answer

O(n)

Answer

Inserting at the beginning requires shifting all existing elements one position to the right, which is O(n).

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