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DSA Oral Question With Answer

  1. List out the areas in which data structures are applied extensively?
    1. Compiler Design,
    2. Operating System,
    3. Database Management System,
    4. Statistical analysis package,
    5. Numerical Analysis,
    6. Graphics,
    7. Artificial Intelligence,
    8. Simulation
2.        What are the major data structures used in the following areas : RDBMS, Network data model and Hierarchical data model.
  1. RDBMS = Array (i.e. Array of structures)
  2. Network data model = Graph
  3. Hierarchical data model = Trees
3.        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.


4.        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.

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.
  1. What are the notations used in Evaluation of Arithmetic Expressions using prefix and postfix forms?
Polish and Reverse Polish notations.
  1. Convert the expression ((A + B) * C - (D - E) ^ (F + G)) to equivalent Prefix and Postfix notations.
    1. Prefix Notation: - * +ABC ^ - DE + FG
    2. Postfix Notation: AB + C * DE - FG + ^ -
  2. 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.
  1. What are the methods available in storing sequential files ?
    1. Straight merging,
    2. Natural merging,
    3. Polyphase sort,
    4. Distribution of Initial runs.
  2. List out few of the Application of tree data-structure?
    1. The manipulation of Arithmetic expression,
    2. Symbol Table construction,
    3. Syntax analysis.
  3. List out few of the applications that make use of Multilinked Structures?
    1. Sparse matrix,
    2. Index generation.
13.  ·  In tree construction which is the suitable efficient data structure? (Array, Linked list, Stack, Queue)
    Linked list is the suitable efficient data structure.

14.  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.
 15.  What is data structure?
Ans: The logical and mathematical model of a particular organization of data is called data structure. There are two types of data structure
i) Linear
ii) Nonlinear
16.   What are the goals of Data Structure?
Ans: It must rich enough in structure to reflect the actual relationship of data in real world.
The structure should be simple enough for efficient processing of data.
17.   What does abstract Data Type Mean?
Ans: Data type is a collection of values and a set of operations on these values. Abstract data type refer to the mathematical concept that define the data type.
It is a useful tool for specifying the logical properties of a data type.
ADT consists of two parts
1) Values definition
2) Operation definition
Example:-The value definition for the ADT RATIONAL states that RATIONAL value consists of two integers, second doesn’t equal to zero.
The operator definition for ADT RATIONAL includes the operation of creation (make rational) addition, multiplication and test for equality.

18 . What is the difference between a Stack and an Array?
Ans:
i) Stack is a ordered collection of items
ii) Stack is a dynamic object whose size is constantly changing as items are pushed and popped .
iii) Stack may contain different data types
iv) Stack is declared as a structure containing an array to hold the element of the stack, and an integer to indicate the current stack top within the array.
ARRAY
i) Array is an ordered collection of items
ii) Array is a static object i.e. no of item is fixed and is assigned by the declaration of the array
iii) It contains same data types.
iv) Array can be home of a stack i.e. array can be declared large enough for maximum size of the stack.
19.. What do you mean by recursive definition?
Ans: The definition which defines an object in terms of simpler cases of itself is called recursive definition.
20 What is sequential search?
Ans: In sequential search each item in the array is compared with the item being searched until a match occurs. It is applicable to a table organized either as an array or as a linked list.
21 What actions are performed when a function is called?
Ans: When a function is called
i) arguments are passed
ii) local variables are allocated and initialized
ii) transferring control to the function
22. What actions are performed when a function returns?
Ans:
i) Return address is retrieved
ii) Function’s data area is freed
iii) Branch is taken to the return address
23 What is a linked list?
Ans: A linked list is a linear collection of data elements, called nodes, where the linear order is given by pointers. Each node has two parts first part contain the information of the element second part contains the address of the next node in the list.
24 What are the advantages of linked list over array (static data structure)?
Ans:
The disadvantages of array are
i) unlike linked list it is expensive to insert and delete elements in the array
ii) One can’t double or triple the size of array as it occupies block of memory space.
In linked list
i) each element in list contains a field, called a link or pointer which contains the address of the next element
ii) Successive element’s need not occupy adjacent space in memory.

25. What are the disadvantages of linear list?
Ans:
i) We cannot reach any of the nodes that precede node (p)
ii) If a list is traversed, the external pointer to the list must be persevered in order to reference the list again
26. Define circular list?
Ans: In linear list the next field of the last node contain a null pointer, when a next field in the last node contain a pointer back to the first node it is called circular list.
Advantages – From any point in the list it is possible to reach at any other point
27. What are the disadvantages of circular list?
Ans:
i) We can’t traverse the list backward
ii) If a pointer to a node is given we cannot delete the node
28. Define double linked list?
Ans: It is a collection of data elements called nodes, where each node is divided into three parts
i) An info field that contains the information stored in the node
ii) Left field that contain pointer to node on left side
iii) Right field that contain pointer to node on right side
29. Is it necessary to sort a file before searching a particular item ?
Ans:
If less work is involved in searching a element than to sort and then extract, then we don’t go for sort
If frequent use of the file is required for the purpose of retrieving specific element, it is more efficient to sort the file.
Thus it depends on situation.
30. What are the issues that hamper the efficiency in sorting a file?
Ans: The issues are
i) Length of time required by the programmer in coding a particular sorting program
ii) Amount of machine time necessary for running the particular program
iii)The amount of space necessary for the particular program .
31. Calculate the efficiency of sequential search?
Ans: The number of comparisons depends on where the record with the argument key appears in the table
If it appears at first position then one comparison
If it appears at last position then n comparisons
Average=(n+1)/2 comparisons
Unsuccessful search n comparisons
Number of comparisons in any case is O (n).
32. Is any implicit arguments are passed to a function when it is called?
Ans: Yes there is a set of implicit arguments that contain information necessary for the function to execute and return correctly. One of them is return address which is stored within the function’s data area, at the time of returning to calling program the address is retrieved and the function branches to that location.
33. Parenthesis is never required in Postfix or Prefix expressions, why?
Ans: Parenthesis is not required because the order of the operators in the postfix /prefix expressions determines the actual order of operations in evaluating the expression
34. List out the areas in which data structures are applied extensively?
Ans:
Compiler Design,
Operating System,
Database Management System,
Statistical analysis package,
Numerical Analysis,
Graphics,
Artificial Intelligence,
Simulation

35. What are the major data structures used in the following areas : network data model & Hierarchical data model.
Ans:
RDBMS – Array (i.e. Array of structures)
Network data model – Graph
Hierarchical data model – Trees
36. If you are using C language to implement the heterogeneous linked list, what pointer type will you use?
Ans: 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.
37. Minimum number of queues needed to implement the priority queue?
Ans: Two. One queue is used for actual storing of data and another for storing priorities.
38. What is the data structures used to perform recursion?
Ans: 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.
39. What are the notations used in Evaluation of Arithmetic Expressions using prefix and postfix forms?
Ans: Polish and Reverse Polish notations.
40. Convert the expression ((A + B) * C – (D – E) ^ (F + G)) to equivalent Prefix and Postfix notations.
Ans: Prefix Notation:
^ – * +ABC – DE + FG
Postfix Notation:
AB + C * DE – – FG + ^

41. Sorting is not possible by using which of the following methods?
(a) Insertion
(b) Selection
(c) Exchange
(d) Deletion
Ans: (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.
42. List out few of the Application of tree data-structure?
Ans:
The manipulation of Arithmetic expression,
Symbol Table construction,
Syntax analysis.
43. List out few of the applications that make use of Multilinked Structures?
Ans: Sparse matrix, Index generation.
44. in tree construction which is the suitable efficient data structure?
(A) Array (b) Linked list (c) Stack (d) Queue (e) none
Ans: (b) Linked list

45. One of the following tree structures, which is, efficient considering space and time complexities?
a) Incomplete Binary Tree.
b) Complete Binary Tree.
c) Full Binary Tree.

Ans:
b) Complete Binary Tree.
By the method of elimination:
Full binary tree loses its nature when operations of insertions and deletions are done. For incomplete binary trees,
extra property of complete binary tree is maintained even after operations like additions and deletions are done on it.
46. What is a spanning Tree?
Ans: 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.
47. Does the minimum spanning tree of a graph give the shortest distance between any 2 specified nodes?
Ans: No.
Minimal spanning tree assures that the total weight of the tree is kept at its minimum. But it doesn’t mean that the distance between any two nodes involved in the minimum-spanning tree is minimum.
48. Whether Linked List is linear or Non-linear data structure?
Ans: According to Storage Linked List is a Non-linear one.

49. What is the type of the algorithm used in solving the 8 Queens problem?
Ans: Backtracking
50. In an AVL tree, at what condition the balancing is to be done?
Ans: If the ‘pivotal value’ (or the ‘Height factor’) is greater than 1 or less than –1.
51. There are 8, 15, 13, 14 nodes were there in 4 different trees. Which of them could have formed a full binary tree?
Ans: 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.
52. In RDBMS, what is the efficient data structure used in the internal storage representation?
Ans: B+ tree. Because in B+ tree, all the data is stored only in leaf nodes, that makes searching easier. This corresponds to the records that shall
be stored in leaf nodes.



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