# (Paper) Data Structures Aptitude (1)

# Data Structures Aptitude

**(Part - 1)**

**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.

**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,

Note - A binary tree with n nodes has exactly n+1 null nodes.

**11.
What are the methods available in storing sequential files ?**

* Straight merging,

* 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.

i ii iii iv v

**In
general:**Note - 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

**16.
What is the type of the algorithm used in solving the 8 Queens problem?**

Backtracking

**17. In
an AVL tree, at what condition the balancing is to be done?**

If the ?pivotal value? (or the ?Height factor?) is greater than 1 or
less than ?1.

**18.
What is the bucket size, when the overlapping and collision occur at same time?**

One. If there is only one entry possible in the bucket, when the collision
occurs, there is no way to accommodate the colliding value. This results in the
overlapping of values.

**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

**16.
What is the type of the algorithm used in solving the 8 Queens problem?**

Backtracking

**17. In
an AVL tree, at what condition the balancing is to be done?**

If the ?pivotal value? (or the ?Height factor?) is greater than 1 or
less than ?1.

**18.
What is the bucket size, when the overlapping and collision occur at same time?**

One. If there is only one entry possible in the bucket, when the collision
occurs, there is no way to accommodate the colliding value. This results in the
overlapping of values.

**19.
Traverse the given tree using Inorder, Preorder and Postorder traversals.**

* Inorder : D H B E A F C I G J * Preorder: A B D H E C F G I J * Postorder: H D E B F I J G C A

**20.
There are 8, 15, 13, 14 nodes were there in 4 different trees. Which of them
could have formed a full binary tree?**

15.

In general:

There are 2n-1 nodes in a full binary tree.

By the method of elimination:

Full binary trees contain odd number of nodes. So there cannot be full binary
trees with 8 or 14 nodes, so rejected. With 13 nodes you can form a complete
binary tree but not a full binary tree. So the correct answer is 15.

Note:

Full and Complete binary trees are different. All full binary trees are complete
binary trees but not vice versa.

**21. In
the given binary tree, using array you can store the node 4 at which location?**

At location 6

1 2 3 - - 4 - - 5 Root LC1 RC1 LC2 RC2 LC3 RC3 LC4 RC4

where LCn means Left Child of node n and RCn means Right Child of node n