Data Structure and Algorithm

Question 1

What is a data structure?

Answer 1

A data structure is a format for arranging, processing, accessing, and storing data. It is designed to organize data for specific uses, making it easier for users to access and manipulate the data they need.

Question 2

What is Big-O notation?

Answer 2

Big-O notation describes the performance or complexity of an algorithm, indicating the worst-case scenario for how the running time grows as the input size increases.

Question 3

What are the types of time complexity in Big-O notation?

Answer 3

O(1): Constant time complexity (operation takes the same time regardless of input size).
O(n): Linear time complexity (time grows linearly with input size).
O(log n): Logarithmic time complexity (time grows logarithmically, dividing the search interval).
O(n²): Squared time complexity (time grows quadratically as input size increases).

Question 4

What is an array data structure?

Answer 4

An array is a data structure containing items of similar data types. It allows for efficient access to elements using indices.

Question 5

What is a linked list?

Answer 5

A linked list is a linear data structure where each element (node) contains two items: the data and a reference to the next node. It is dynamic and can grow/shrink in size as needed.

Question 6

What is the difference between stacks and queues?

Answer 6

Stacks follow Last-In-First-Out (LIFO). Operations: push (add element), pop (remove element).
Queues follow First-In-First-Out (FIFO). Operations: enqueue (add element), dequeue (remove element).

Question 7

What is a HashMap?

Answer 7

A HashMap stores key-value pairs, where each key is hashed to a hash code for efficient access.

Question 8

What is a tree data structure?

Answer 8

A tree is a hierarchical data structure with nodes connected by edges. Each node contains a value and may have child nodes. A binary tree is a special type of tree where each node has at most two children.

Question 9

What is O(1) complexity in an algorithm?

Answer 9

O(1), or constant time complexity, refers to operations that take a fixed amount of time regardless of the size of the input.

Question 10

How does a binary search tree (BST) work?

Answer 10

A binary search tree allows inserting numbers and searching for specific values. Each node has at most two children, with the left child being less than the parent node, and the right child being greater. It allows efficient searching, insertion, and deletion.

Question 11

What is the purpose of a queue?

Answer 11

A queue is used for handling data in a First-In-First-Out (FIFO) order, which is ideal for scheduling tasks, managing resources, or processing data streams.

Question 12

What is the push operation in a stack?

Answer 12

The push operation adds an element to the top of the stack in a Last-In-First-Out (LIFO) order.

Question 13

What is the pop operation in a stack?

Answer 13

The pop operation removes the top element from the stack, adhering to the Last-In-First-Out (LIFO) principle.

Question 14

What does enqueuing mean in a queue?

Answer 14

Enqueuing means adding an element to the end of the queue, following the First-In-First-Out (FIFO) order.

Question 15

What does dequeuing mean in a queue?

Answer 15

Dequeuing means removing an element from the front of the queue, adhering to the First-In-First-Out (FIFO) principle.

Question 16

What is the insert operation in a binary search tree (BST)?

Answer 16

The insert operation adds a new node in the correct position in the tree, ensuring that the left child is smaller and the right child is larger than the parent node.

Question 17

How would you search for an element in a binary search tree?

Answer 17

To search for an element in a BST, start at the root and compare the element with the current node’s value. If the element is smaller, move to the left child; if it is larger, move to the right child. Continue this process until the element is found or the search reaches a null node.

Question 18

What is the peek operation in a stack or queue?

Answer 18

The peek operation retrieves the top element of a stack or the front element of a queue without removing it, allowing you to view the next element to be processed.

Question 19

What is dynamic memory allocation in the context of a linked list?

Answer 19

Dynamic memory allocation refers to the process of allocating memory as needed during runtime, allowing the size of the linked list to grow or shrink dynamically without the need for a predefined size.

Question 20

Why would you choose a linked list over an array for a collection of items?

Answer 20

A linked list is more suitable for frequent additions or deletions since it doesn’t require resizing or shifting elements like an array does. It dynamically grows and shrinks, unlike fixed-size arrays.