### Interview Questions :: Data Structure

**1. What is data structure?**

A data structure is a way of organizing data that considers not only the items stored, but also their relationship to each other. Advance knowledge about the relationship between data items allows designing of efficient algorithms for the manipulation of data.

**2.List out the areas in which data structures are applied extensively?**

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

**3. What are the major data structures used in the following areas : RDBMS, Network data model and Hierarchical data model.**

- RDBMS = Array (i.e. Array of structures)
- Network data model = Graph
- Hierarchical data model = Trees

**4. If you are using C language to implement the heterogeneous linked list, what pointer type will you use?**

The heterogeneous linked list contains different data types in its nodes and we need a link, pointer to connect them. It is not possible to use ordinary pointers for this. So we go for void pointer. Void pointer is capable of storing pointer to any type as it is a generic pointer type.

**5. What is the data structures used to perform recursion?**

Stack. Because of its LIFO (Last In First Out) property it remembers its ‘caller’ so knows whom to return when the function has to return. Recursion makes use of system stack for storing the return addresses of the function calls.

Every recursive function has its equivalent iterative (non-recursive) function. Even when such equivalent iterative procedures are written, explicit stack is to be used.

**6. Convert the expression ((A + B) * C – (D – E) ^ (F + G)) to equivalent Prefix and Postfix notations.**

**Prefix Notation:**– * +ABC ^ – DE + FG**Postfix Notation:**AB + C * DE – FG + ^ –

**7. Sorting is not possible by using which of the following methods? (Insertion, Selection, Exchange, Deletion)**

**Sorting is not possible in Deletion.**Using insertion we can perform insertion sort, using selection we can perform selection sort, using exchange we can perform the bubble sort (and other similar sorting methods). But no sorting method can be done just using deletion.

**8. Classify the Hashing Functions based on the various methods by which the key value is found.**

- Direct method,
- Subtraction method,
- Modulo-Division method,
- Digit-Extraction method,
- Mid-Square method,
- Folding method,
- Pseudo-random method.

**9. What is a spanning Tree?**

A spanning tree is a tree associated with a network. All the nodes of the graph appear on the tree once. A minimum spanning tree is a spanning tree organized so that the total edge weight between nodes is minimized.

**10. Whether Linked List is linear or Non-linear data structure?**

According to Access strategies Linked list is a linear one.

According to Storage Linked List is a Non-linear one.

According to Storage Linked List is a Non-linear one.