Data Structure Aptitude Questions & Answers

[VelMurugan]

DATA STRUCTURE APPTITUDE

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 & 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. Minimum number of queues needed to implement the priority queue?
Two. One queue is used for actual storing of data and another for storing
priorities.

6. 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.

7. What are the notations used in Evaluation of Arithmetic Expressions using prefix and
postfix forms?
Polish and Reverse Polish notations.

8. 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 + ^

9. Sorting is not possible by using which of the following methods?
(a) Insertion
(b) Selection
(c) Exchange
(d) Deletion
(d) 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.

10. A binary tree with 20 nodes has null branches?
21
Let us take a tree with 5 nodes (n=5)

It will have only 6 (ie,5+1) null branches. In general,
A binary tree with n nodes has exactly n+1 null nodes.

11. What are the methods available in storing sequential files ?
Straight merging,
Null Branches
Natural merging,
Polyphase sort,
Distribution of Initial runs.

12. How many different trees are possible with 10 nodes ?
1014
For example, consider a tree with 3 nodes(n=3), it will have the maximum
combination of 5 different (ie, 23 - 3 = 5) trees.


In general:
If there are n nodes, there exist 2n-n different trees.

13. List out few of the Application of tree data-structure?
The manipulation of Arithmetic expression,
Symbol Table construction,
Syntax analysis.

14. List out few of the applications that make use of Multilinked Structures?
Sparse matrix,
Index generation.

15. In tree construction which is the suitable efficient data structure?
(a) Array (b) Linked list (c) Stack (d) Queue (e) none
(b) Linked list


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[Siddeshwapa]

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