**Data Structure Interview Questions PDF | Data Structure Interview Questions for Freshers | Data Structure Interview Questions for Experience**

**Data Structure Interview Questions:** Data Structure is the basis of software engineering. Here we have shared the latest Data Structure Interview Questions and answers. This Data Structure questions will be helpful to crack any interview /various competitive examination. You have to download the Data Structure Interview Questions PDF link and start your preparation for interview. Practice in interview questions on Data structure, it will improve your performance in the Exams and Interview. Under mentioned Data Structure interview questions are frequently asked in interview. So candidate who aspire to join the Data structure jobs, kindly use this Data Structure Important Interview Questions. Both freshers and experienced can also use this frequently asked Data structure questions with answers.

**Details for Important Data Structure Interview Questions & Answers**

Name of the Topic | Data Structure |

Total Questions | 30 |

Category | Interview Questions |

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**Data Structure Interview Questions**

**1. What is the difference between PUSH and POP?**

PUSH |
POP |

PUSH specifies that data is being “inserted” into the stack | POP specifies data retrieval. It means that data is being deleted from the stack |

**2. Which data structure is used to perform recursion? **

- Stack data structure is used in recursion due to its last in first out nature.
- Operating system maintains the stack in order to save the iteration variables at each function call

**3. What is an array?**

- Arrays are defined as the collection of similar types of data items stored at contiguous memory locations.
- It is the simplest data structure in which each data element can be randomly accessed by using its index number.

**4. What is a postfix expression?**

- An expression in which operators follow the operands is known as postfix expression.
- The main benefit of this form is that there is no need to group sub-expressions in parentheses or to consider operator precedence.

**5. What are the operations that can be performed on a stack?**

- Push Operations
- Pop Operations
- Peek Operations

**6. List the data structures which are used in ****Network Data Modal, Hierarchical Data Model and ****RDBMS?**

- Network data model uses Graph
- Hierarchal data model uses Trees
- RDBMS uses Array data structure

**7. List the area of applications where stack data structure can be used?**

- Memory Management
- Function calling and return
- Expression evaluation
- Backtracking

**8. What is a multidimensional array?**

- The multidimensional array can be defined as the array of arrays in which, the data is stored in tabular form consists of rows and columns.
- 2D arrays are created to implement a relational database lookalike data structure.
- It provides ease of holding the bulk of data at once which can be passed to any number of functions wherever required.

**9. Define Linked List Data structure.**

- Linked List is the collection of randomly stored data objects called nodes. In Linked List, each node is linked to its adjacent node through a pointer. A node consist two fields such as Data Field and Link Field.

**10. How to reference all the elements in a one-dimension array?**

- It can be done by using an indexed loop such that the counter runs from 0 to the array size minus one. In this manner, you can reference all the elements in sequence by using the loop counter as the array subscript.

**11. What are the advantages of Linked List over an array?**

- The List is not required to be contiguously present in the main memory, if the contiguous space is not available, the nodes can be stored anywhere in the memory connected through the links.
- The List is dynamically stored in the main memory and grows as per the program demand while the array is statically stored in the main memory, size of which must be declared at compile time.
- The number of elements in the linked list are limited to the available memory space while the number of elements in the array is limited to the size of an array

**12. What is Data Structure?**

- The data structure is a way that specifies how to organize and manipulate the data.
- Defines the relationship between them.

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

- Row-Major Order: In row-major ordering, all the rows of the 2D array are stored into the memory contiguously.
- First, the 1st row of the array is stored into the memory completely, then the 2nd row of the array is stored into the memory completely and so on till the last row.
- Column-Major Order: In column-major ordering, all the columns of the 2D array are stored into the memory contiguously.
- First, the 1st column of the array is stored into the memory completely, then the 2nd row of the array is stored into the memory completely and so on till the last column of the array.

**14. What is a Stack?**

- Stack is an ordered list in which, insertion and deletion can be performed only at one end that is called the top.
- It is a recursive data structure having pointer to its top element.
- The stack is sometimes called as Last-In-First-Out.

**15. What is doubly linked list?**

- The doubly linked list is a complex type of linked list in which a node contains a pointer to the previous as well as the next node in the sequence.

**16. List the area of applications of Data Structure.**

- Statistical analysis package,
- Numerical Analysis,
- Graphics,
- Artificial Intelligence,
- Simulation.
- Compiler Design,
- Operating System,
- Database Management System

**17. Define the graph data structure?**

- A graph G can be defined as an ordered set G(V, E) where V(G) represents the set of vertices and E(G) represents the set of edges which are used to connect these vertices.
- A graph can be seen as a cyclic tree, where the vertices (Nodes) maintain any complex relationship among them instead of having parent-child relations.

**18. What is the minimum number of queues that can be used to implement a priority queue?**

- Two queues are needed. One queue is used to store the data elements, and another is used for storing priorities.

**19. List some applications of Tree-data structure?**

- The manipulation of Arithmetic expression,
- Symbol Table construction,
- Syntax analysis
- Hierarchal data model

**20. Mention the data structures which are used in graph implementation.**

- In sequential representation, Adjacency matrix is used.
- In Linked representation, Adjacency list is used.

**21 What is a dequeue?**

- Dequeue also known as double-ended queue can be defined as an ordered set of elements in which the insertion and deletion can be performed at both the ends, i.e. front and rear.

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

B Tree |
B+ Tree |

Search keys cannot repeatedly be stored. | Redundant search keys can be present. |

Deletion of internal nodes is so complicated and time-consuming. | Deletion will never be a complexed process since element will always be deleted from the leaf nodes |

Leaf nodes cannot be linked together. | Leaf nodes are linked together to make the search operations more efficient. |

**23. What are Binary trees?**

- A binary Tree is a special type of generic tree in which, each node can have at most two children. Binary tree is generally partitioned into three disjoint subsets, i.e. the root of the node, left sub-tree and Right binary sub-tree.

**24. What are the types of Data Structures?**

- Linear Data Structure
- Non-Linear Data Structure

**25. What are the drawbacks of array implementation of Queue?**

- Memory Wastage: The space of the array, which is used to store queue elements, can never be reused to store the elements of that queue because the elements can only be inserted at front end and the value of front might be so high so that, all the space before that, can never be filled.
- Array Size: There might be situations in which, we may need to extend the queue to insert more elements if we use an array to implement queue, It will almost be impossible to extend the array size, therefore deciding the correct array size is always a problem in array implementation of queue.

**26. List the types of tree.**

- General Tree
- Forests
- Binary Tree
- Binary Search Tree
- Expression Tree
- Tournament Tree

**27. List some applications of queue data structure.**

- Queues are widely used as waiting lists for a single shared resource like a printer, disk, CPU.
- Queues are used as buffers in most of the applications like MP3 media player, CD player, etc.
- Queues are used to maintain the playlist in media players to add and remove the songs from the play-list.
- Queues are used in operating systems for handling interrupts

**28. State the properties of B Tree.**

- Every node in a B-Tree contains at most m children.
- Every node in a B-Tree except the root node and the leaf node contain at least m/2 children.
- The root nodes must have at least 2 nodes.
- All leaf nodes must be at the same level.

**29. Define the tree data structure.**

- The Tree is a recursive data structure containing the set of one or more data nodes where one node is designated as the root of the tree while the remaining nodes are called as the children of the root.
- The nodes other than the root node are partitioned into the nonempty sets where each one of them is to be called sub-tree.

**30. Define the queue data structure.**

- A queue can be defined as an ordered list which enables insert operations to be performed at one end called REAR and delete operations to be performed at another end called FRONT.

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