**Data structure Interview Questions and answer**

Here we will discuss **Data structure Interview Questions and answer**.You might be curious about the types of questions you’ll be asked during your next data structure interview. Just keep in mind that data structure interviewers aren’t attempting to fool you, and they don’t expect perfection, but it is their chance to assess your understanding before investing in your job. It’s usually a good idea to plan ahead.

**Data structure Interview Questions and answer** to any programming job interview, especially one for a Data Science or Java-based post, should include data structures and algorithm questions. Knowing how to think in terms of data structures and algorithms will help you stand out from the crowd. The Data Structure interview questions below will assist you in acing your next interview!

**1.What is a Data Structure? **

A data structure is a method of organising data in such a way that it may be used effectively. Different data structures are better suited to different applications, and some are highly specialised for certain tasks. B-trees, for example, are well-suited for database implementation, but compiler implementations typically employ hash tables to look for identifiers.

The way data is arranged and modified is referred to as data structure. It aims to improve the efficiency of data access. When dealing with data structure, we don’t only focus on one piece of data, but on several different sets of data and how they might be organised.

The Data Structure is how information is coordinated (put away) and controlled for recovery and access. It additionally characterizes the manner in which various arrangements of information connect with each other, laying out connections and framing calculations.

**2.What are linear and non-linear data Structures? **

**Linear: **If the elements of a data structure form a sequence or a linear list, it is said to be linear. Array is an example. Stacks, Queues, and Linked Lists

**Non-Linear: **If the traversal of nodes is nonlinear, the data structure is said to be non-linear. Graphs and Trees are two examples.

**3. Differentiate between file and structure storage structure.**

The memory area that is accessed is the main distinction between the two data structures. Storage structure is the term used to describe the structure in which the computer system’s main memory is housed. We refer to auxiliary structures as file structures when interacting with them.

**4. 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 a multi-layered array. The two-dimensional array, or 2D array, is the most basic multidimensional array. It’s technically an array of arrays, as you’ll see in the code. A two-dimensional array is also known as a matrix or a table with rows and columns. A one-dimensional array is the same thing as a multidimensional array. For a two-dimensional array, we must inform C that we have two dimensions.

**5. How are the elements of a 2D array stored in the memory?**

All of the rows of a 2D array are kept in memory in a continuous manner in row-major ordering.First, the array’s first row is totally saved in memory, followed by the array’s second row, and so on until the array’s final row.

Column-Major Order: Column-major ordering stores all of the columns in a 2D array in the same order in memory. The first column of the array is completely saved in memory, followed by the second row, and so on until the last column is completely saved in memory.

**6. What is a linked list Data Structure?**

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

It’s a linear Data Structure, or a sequence of data items, in which the elements aren’t kept in the same memory address. To build a chain, the items are linked using 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, and the last node is a null reference when the list is empty.

**7. Are linked lists considered linear or non-linear Data Structures?**

Linked lists are classified as either linear or non-linear data structures, depending on the application. It’s a linear data structure when it’s used for access methods. It’s a non-linear data structure when it’s utilised for data storage.

**8. What are the advantages of a linked list over an array? In which scenarios do we use Linked List and when Array?**

This is yet another data structure interview question that is regularly asked! The following are some of the advantages of a linked list over an array:

Insertion and deletion are the first two steps in the process.The procedure of adding and removing nodes is simplified because we merely change the address in the node’s next pointer. It’s more expensive to accomplish the same in an array since space must be made for new components and current elements must be relocated.

Because a linked list is a dynamic data structure, no starting size is required because it can grow and shrink at runtime.

**9 When is a binary search best applied?**

A binary search is an algorithm that works best when the entries in a list are already sorted or in order. The list is searched from the middle, therefore if that middle value is not the target search key, it will check to determine if the search should continue on the bottom half or the upper half of the list. After then, the split and search will proceed in the same manner.

**10. Why do we need to do an algorithm analysis?**

Several solution algorithms can be used to solve a problem in more than one way. Algorithm analysis estimates the resources required by an algorithm to solve a certain computer task. It’s also decided how much time and space are needed to complete the task.

The time complexity of an algorithm measures how long an algorithm takes to run as a function of the length of the input. 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.

**11. What is a stack?**

A stack is an abstract data type that provides a linear data structure, similar to a physical stack or pile in which you may only remove the top item to remove items. Thus, item insertion (push) and deletion (pop) occur only at one end of the stack, known as the top of the stack, and in a specific order: LIFO (Last In First Out) or FILO (First In Last Out) (First In Last Out).

**12. What is a queue Data Structure? **

You can also share your experience and scenarios with queue in this data structure interview question. The First In First Out (FIFO) action is used to access entries in a queue, which is an abstract data type that describes a linear data structure or an ordered list. Only one end, referred to as REAR, may perform insert operations, while the other end, referred to as FRONT, can perform deletion actions.

**13. What are some examples of divide and conquer algorithms?**

The sorting algorithm Quicksort is named after. The method chooses a pivot element and rearranges the array components so that all items less significant than the pivot element go to the left side and all elements more substantial than the pivot element go to the right side.

Merge Sort is also a sorting algorithm. The algorithm splits the array into two parts, sorts them recursively, and then joins the two halves together. The goal of finding the closest pair of points in an x-y plane collection of points is called “points that are closest together.” By computing the distances between each pair of places and comparing them to identify the shortest distance, the problem can be completed in O(n2) time.

**14. What are the differences between the B tree and the B+ tree?**

The B tree is an m-way self-balancing tree, with m indicating the order of the tree. Btree is an extension of the Binary Search tree in which a node can have more than one key and more than two children, depending on the number of m. The information is sorted in the B tree, with lower values on the left subtree and higher values on the right subtree.

Because every path from the tree’s root to its leaf is the same length, the B+ tree is an advanced self-balanced tree. Because all of the leaf nodes are the same length, they all occur at the same level. Some leaf nodes aren’t allowed to emerge at the third level, whereas others can.

**15. Do dynamic memory allocations help in managing data? How?**

At runtime, dynamic memory allocation saves simple structured data types. It may combine individually allocated structured blocks to construct composite structures that expand and contract as needed, making it easier to manage data blocks of any size and in any order.

**16) What is LIFO?**

Last In First Out is abbreviated as LIFO. It refers to the methods for accessing, storing, and retrieving data. The data that was stored last should be extracted first, according to this scheme. This also implies that in order to access the first data, all previous data must be retrieved and extracted first.

**17) Explain Binary Search Tree**

A binary search tree stores data in a form that allows it to be accessed quickly. Nodes whose keys are less than the node’s key value are in the left subtree, while nodes whose keys are larger than or equal to the node’s key value are in the right subtree. In addition, both subtrees are binary search trees.

**18) What is merge sort?**

Merge sorting is a divide-and-conquer method of data sorting. To build larger sorted lists, nearby data in a sequence is combined and sorted. These sorted lists are then merged once again to generate a larger sorted list, and so on until there is only one sorted list left.

**19) What is the difference between a PUSH and a POP?**

The way data is stored and retrieved in a stack is referred to as “pushing and popping.” A push indicates that data is being added to the stack, implying that data is being “pushed” into it. A pop, on the other hand, implies data retrieval and, more specifically, refers to the most recent data accessed.

**20 How does a selection sort work for an array?**

The selection sort is a simple sorting algorithm, although it isn’t always efficient. The smallest element is located first and exchanged with the element at subscript zero, resulting in the smallest element being placed first.

The subarray’s smallest element is then moved next to subscripts 1 through n-1 and swapped with the element at subscript 1, putting the second smallest element in the second position. The stages are continued until the last element is reached.

**Related Links to Data structure Interview Questions and answer**

https://career.guru99.com/top-50-data-structure-interview-questions/

https://www.simplilearn.com/data-structure-interview-questions-and-answers-article

https://www.interviewbit.com/data-structure-interview-questions/