Data structure interview questions | Most frequently questions

Computers have been the key factor behind every discipline’s advancement and progression. With rapid developments in business and other industries, the ability to handle large amounts of data has become critical. To meet the need, new areas such as data analytics and data science have exploded in terms of employment. Students often have difficulty answering data structure interview questions when applying for their dream jobs. But if properly prepared, it can be an easy breeze to ace the interview round!

What is a stack?

A stack is an ordered list in which insertion and deletion are only possible at one end, the top. It’s a recursive data structure with a top element pointer. The stack is also known as a Last-In-First-Out (LIFO) list because the piece entered first in the stack is removed last.

What is an array?

Arrays are collections of comparable sorts of data kept nearby in memory.

It is the most basic data structure in which a data element may be retrieved at random using its index number alone.

What is a multidimensional array?

A multidimensional array is an array that has more than one dimension. It’s either an array of arrays or an array with several levels. The two-dimensional array, or 2D array, is the simplest basic multidimensional array. It’s technically an array of arrays, as you’ll see in the code. A 2D array is also known as a matrix or a table with rows and columns. For a 2D l array, we must inform C that we have two dimensions.

What is a linked list data structure?

This is one of the most common data structure interview questions, and the interviewer wants you to provide a detailed response. Instead of concluding your answer in a phrase, try to describe as much as possible!

It’s a linear data structure or a succession of data objects in which the elements aren’t kept in the same memory address. A chain is formed by connecting the elements with pointers. Each element is a distinct entity known as a node. A data field and a reference to the next node are both present in each node. The head is the starting point of a linked list. The head is a null reference. The final node is also a null reference when the list is empty.

A linked list is a dynamic data structure with an unlimited number of nodes and the capacity to grow and shrink on demand.

What are the advantages of a linked list over an array?

• A linked list’s size may be increased at runtime, which is not feasible with an array.
• The List does not need to be contiguous in the main memory. If contiguous space is not available, the nodes can be put anywhere in the memory and connected by links.
• The List is dynamically stored in the main memory and expands in response to program demands, whereas the array is statically kept in the main memory and must have a size defined at build time.
• The linked list’s number of items is limited by available memory space, whereas the array’s number of elements is limited by the array’s size.

Why do we need an algorithm analysis?

Several solution algorithms can be used to tackle an issue. Algorithm analysis estimates the resources required by an algorithm to solve a certain computer task. The quantity of time and space needed to complete the task is also calculated with the help of algorithm analysis.

The time complexity of an algorithm measures how long an algorithm takes to run as a function of the length of the input. Whereas, the space complexity of an algorithm is a measure of how much space or memory it takes to run as a function of the length of the input.

How does binary search work?

This is yet another important data structure interview question. Here’s how you should answer it.

When efficiency is the primary criterion, a binary search is performed. It entails dealing with material that has previously been sorted in either ascending or descending order. The search begins with the center element in the array, which is discovered first. The array is divided into two halves based on whether the search value is more than or less than the middle member. Knowing the sequence of the arrangement is essential for finding the value.

What is a merge sort?

Merge sorting is a sorting method based on the divide-and-conquer strategy. In every iteration, data entities that are next to each other are first merged and arranged to build sorted lists. In the end, these smaller sorted lists are linked together to make a fully sorted list.

What is the working of a selection sort?

In the data structures front, a selection sort is a frequently used sorting algorithm. The process is straightforward – the smallest object is located first, and its index is set to zero, permanently sorting it in the first step. The last stages entail iterating over the remaining items and adding the next index if needed. This process is repeated until all the items have been sorted.

How does a Huffman’s algorithm work?

The frequency of occurrence of each data object in the list is stored in a table in Huffman’s algorithm. This is used to make extended binary trees, which are known to have the shortest path lengths. This takes into account all the appropriate weights.

What does a deque mean?

Describing a deque also turns out to be a significant aspect of the data structure interview questions.

A double-ended queue is known as a deque. This means that any of the two ends can have items added or deleted. It may function as both a standard queue and a stack. In general, it outperforms both linked lists and stacks.

What we have to say

• Present yourself by being well prepared throughout your interview and taking time to think about and arrange your responses beforehand. 
• If you have any reservations about a question, rather than avoiding it, it is best to brush up on your knowledge of the subjects.

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FAQ’s

Q1. What are the 4 data structures?

Answer – The 4 data structures are as follows – 

• Array data structure
• Stack data structure
• Queue data structure
• Linked list data structure

Q2. Which language is the best for a data structure?

Answer – The best language for a data structure is – 

• Python
• Java script
• Java
• C++
• C#
• Golang
• Swift
• PHP

Q3. What is a data structure in C?

Answer – The data structure in C is used to store data in an organized manner.