FAQ’s during Campus Placement
Data Structures
About Technical Interviews
A technical interview is a type of interview that typically features questions that are specific to
the role you have applied for. Technical interviews are generally used to assess candidates for
technical or specialist graduate job positions (such as jobs in IT, Engineering and Science) rather
than general graduate schemes.
In a technical interview candidates are likely to be asked questions that relate to specific
knowledge about the company's technical activities relate to understanding the technical work
required to be completed as part of the job applied for relate to work completed as part of a
degree course (if this relates to the job applied for) require candidates to solve actual technical
problems that they would be likely to face if employed.
Data Structure Interview Questions-Interview Questions and Answers
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.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.
3.What are the notations used in Evaluation of Arithmetic Expressions
using prefix and postfix forms?
Polish and Reverse Polish notations.
4.List out few of the Application of tree data-structure?
i)The manipulation of Arithmetic expression
ii)Symbol Table construction
iii)Syntax analysis.
5.What is the type of the algorithm used in solving the 8 Queens
problem?
Backtracking
6.In RDBMS, what is the efficient data structure used in the internal
storage representation?
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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.
7. 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.
8. 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
9. Translate infix expression into its equivalent post fix expression:
(A-B)*(D/E)
(A-B)*(D/E) = [AB-]*[DE/] = AB-DE/*
10. What are priority queues?
A priority queue is a collection of elements such that each element
has been assigned a priority.
11. What is a string?
A sequential array of characters is called a string.
12. What is Brute Force algorithm?
Algorithm used to search the contents by comparing each element of
array is called Brute Force algorithm.
13. What are the limitations of arrays?
i)Arrays are of fixed size.
ii)Data elements are stored in continuous memory locations which may
not be available always.
iii)Adding and removing of elements is problematic because of shifting
the locations.
14. How can you overcome the limitations of arrays?
Limitations of arrays can be solved by using the linked list.
15. What is a linked list?
Linked list is a data structure which store same kind of data elements
but not in continuous memory locations and size is not fixed. The
linked lists are related logically.
16. What is a node?
The data element of a linked list is called a node.
17. What does node consist of?
Node consists of two fields:data field to store the element and link
field to store the address of the next node.
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18. What is a queue ?
A Queue is a sequential organization of data. A queue is a first in
first out type of data structure. An element is inserted at the last
position and an element is always taken out from the first position.
19. What are the types of Collision Resolution Techniques and the
methods used in each of the type?
Open addressing (closed hashing),The methods used include:Overflow
block Closed addressing (open hashing),The methods used include:Linked
list,Binary tree
20. What are the methods available in storing sequential files ?
Straight merging, Natural merging, Polyphase sort, Distribution of
Initial runs.
21. Mention some of the problem solving strategies?
The most widely strategies are listed below
i)Divide and conquer
ii)Binary doubling strategy
iii)Dynamic programming
22. What is divide and conquer method?
The basic idea is to divide the problem into several sub problems
beyond which cannot be further subdivided. Then solve the sub problems
efficiently and join then together to get the solution for the main
problem.
23. What is the need for the header?
Header of the linked list is the first element in the list and it
stores the number of elements in the list. It points to the first data
element of the list.
24. Define leaf?
In a directed tree any node which has out degree o is called a
terminal node or a leaf.
25. What are the applications of binary tree?
Binary tree is used in data processing.
26. What are the different types of traversing?
The different types of traversing are
i)Pre-order traversal-yields prefix from of expression.
ii)In-order traversal-yields infix form of expression.
iii)Post-order traversal-yields postfix from of expression.
27. Define pre-order traversal?
i)Process the root node
ii)Process the left subtree
iii)Process the right subtree
28. Define post-order traversal?
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i)Process the left subtree
ii)Process the right subtree
iii)Process the root node
29. Define in -order traversal?
i)Process the left subtree
ii)Process the root node
iii)Process the right subtree
30. What is meant by sorting?
Ordering the data in an increasing or decreasing fashion according to
some relationship among the data item is called sorting.
31. What's the major distinction in between Storage structure and file
structure and how?
The expression of an specific data structure inside memory of a
computer system is termed storage structure in contrast to a storage
structure expression in auxiliary memory is normally known as a file
structure.
32. Stack can be described as a pointer. Explain?
Because stack will contain a head pointer which will always point to
the top of the Stack.All Stack Operations are done using Head Pointer.
Hence Stack can be Described as a Pointer
33. What do you mean by: Syntax Error, Logical Error, Run time Error?
Syntax Error-Syntax Error is due to lack of knowledge in a specific
language. It is due to somebody does not know how to use the features
of a language.We can know the errors at the time of compilation.
logical Error-It is due to the poor understanding of the requirement
or problem.
Run time Error-The exceptions like divide a number by 0,overflow and
underflow comes under this.
34. What is mean by d-queue?
D-queue stands for double ended queue. It is a abstract data structure
that implements a queue for which elements can be added to front or
rear and the elements can be removed from the rear or front. It is
also called head-tail linked list
35. What is AVL tree?
Avl tree is self binary tree in which balancing factor lie between the
-1 to 1.It is also known as self balancing tree.
36. what is binary tree?
Binary tree is a tree which has maximum no. of childrens either 0 or 1
or 2. i.e., there is at the most 2 branches in every node.
37. What is the difference between a stack and a Queue?
Stack – Represents the collection of elements in Last In First Out
order.
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Operations includes testing null stack, finding the top element in the
stack, removal of top most element and adding elements on the top of
the stack.
Queue - Represents the collection of elements in First In First Out
order.Operations include testing null queue, finding the next element,
removal of elements and inserting the elements from the queue.
Insertion of elements is at the end of the queue.Deletion of elements
is from the beginning of the queue
38. What actions are performed when a function is called?
i)arguments are passed
ii)local variables are allocated and initialized
iii)transferring control to the function
39. What is precision?
Precision refers the accuracy of the decimal portion of a value.
Precision is the number of digits allowed after the decimal point.
40. What do you mean by overflow and underflow?
When new data is to be inserted into the data structure but there is
no available space i.e.free storage list is empty this situation is
called overflow.When we want to delete data from a data structure that
is empty this situation is called underflow.
Data Structure Advanced-Interview Questions and Answers
1. Is it possible to find a loop in a Linked list ?
a. Possilbe at O(n)
b. Not possible
c. Possible at O(n^2) only
d. Depends on the position of loop
Solution: a. Possible at O(n)
Have two pointers say P1 and P2 pointing to the first node of the
list. Start a loop and Increment P1 once and P2 twice in each
iteration. At any point of time if P1==P2 then there is a loop in that
linked list. If P2 reaches NULL (end of linked list) then no loop
exists.
2. Two linked lists L1 and L2 intersects at a particular node N1 and
from there all other nodes till the end are common. The length of the
lists are not same. What are the possibilities to find N1?.
a. Solution exist for certain cases only
b. No linear solution exist
c. Linear solution is possible
d Only Non-linear solution exist.
Solution: c. Linear solution is possible
Have two pointers say P1 pointing to the first node of L1 and P2 to
that of L2.
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Traverse through both the lists. If P1 reaches L1’s last node, point
it to the first node of L2 and continue traversing. Do the same thing
for P2 when it reaches L2’s last node. (By doing this, we are
balancing the difference in the length between the linked lists. The
shorter one will get over soon and by redirecting to longer list’s
head, it will traverse the extra nodes also.) Finally they will Meet
at the Intersection node.
3. void PrintTree (Tree T)
{
if (T != NULL)
{
PrintTree (T-> Left);
PrintElement (T-> Element);
PrintTree (T->Right);
}
}
The above method ‘PrintTree’ results in which of the following
traversal
a Inorder
b. Preorder
c. Postorder
d. None of the above
Solution: a. Inorder
Inorder:
void PrintTree (Tree T)
{
if (T != NULL)
{
PrintTree (T-> Left);
PrintElement (T-> Element);
PrintTree (T->Right);
}
}
For preorder use this order
PrintElement (T-> Element);
PrintTree (T-> Left);
PrintTree (T->Right);
For postorder use this order
PrintTree (T-> Left);
PrintTree (T->Right);
PrintElement (T-> Element);
4. Given a Binary Search Tree (BST), print its values in ascending
order.
a.
b.
c.
d.
Perform
Perform
Perform
Perform
Depth first traversal
Breadth first traversal
Postorder traversal
Inorder traversal
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Solution: d. Perform Inorder traversal
It is the properfy of BST and Inorder traversal.
5. Is it possible to implement a queue using Linked List ?. Enqueue &
Dequeue should be O(1).
a. Not possible to implement.
b Only Enqueue is possible at O(1).
c. Only Dequeue is possible at O(1).
d. Both Enqueue and Dequeue is possible at O(1)
Solution: d. Both Enqueue and Dequeue is possible at O(1)
Have two pointers H pointing to the Head and T pointing to the Tail
of the linked list. Perform enqueue at T and perform dequeue at H.
Update the pointers after each operations accordingly.
6. Given a Tree, is it possible to find the greatest and least among
leaves in linear time?.
a. Solution depends on the tree structure
b.Linear solution exist
c. Only Non-linear solution exist.
d. No linear solution exist
Solution: b. Linear solution exist
Have two variables Min and Max. Perform any tree traversal.Assign the
first traversed leaf element to Min and Max for all other leaf
elements check with these variables and update it accordingly. If a
current element is < Min then update Min with that element. If it is >
Min then check with Max.
Note: If you want to find the greatest and least among all nodes
perform the checks for each node traversed.
7. Is it possible to find find the greatest and least value among the
nodes in a given BST without using any extra variables?
a. No solution exist.
b. Solution need 2 extra variables
c. Solution exist without any extra variables
d Solution need 1 extra variable
Solution:c Solution exist without any extra variables
As per BST property, the left most node should be the least one and
the rightmost node should be the greatest. In other words, the first
and last node of an Inorder traversal are the least and greatest among
the nodes respectively.
8. Is it possible to implement 2 stack in an array?
Condition: None of the stack should indicate an overflow until every
slot of an array is used.
a. Only 1 stack can be implemented for the given condition
b. Stacks can not be implemented in array
c. 2 stacks can be implemented for the given condition.
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d. 2 stacks can be implemented if the given condition is applied only
for 1 stack.
Solution:c. 2 stacks can be implemented for the given condition
Start 1st stack from left (1st position of an array) and 2nd from
right (last position say n). Move 1st stack towards right( i.e 1,2,3
...n) and 2nd towards left (i.e n,n-1,n-2...1).
9. Given two keys K1 & K2, write an algorithm to print all the
elements between them with K1<=K2 in a BST.
a. Solution need 2 extra spaces
b. Linear solution is possible without using any extra space
c No linear solution exist
d Solution need 1 extra space
Solution:b. Linear solution is possible without using any extra space
Perform an inorder traversal. Once you find K1 print it and continue
traversal now, print all other traversed elements until you reach K2.
Note: If K1 == K2 stop once you find K1.
10. How many stacks are required to implement a Queue.
a. One
b. Two
c. Three
d. Two + one extra space.
Solution:b Two
Have two stacks S1 and S2.
For Enqueue, perform push on S1.
For Dequeue, if S2 is empty pop all the elements from S1 and push it
to S2. The last element you popped from S1 is an element to be
dequeued. If S2 is not empty, then pop the top element in it.
Data structure interview questions
1. What is Data Structure?
- Data structure is a group of data elements grouped together under
one name.
- These data elements are called members. They can have different
types and different lengths.
- Some of them store the data of same type while others store
different types of data.
2. Which data structure is used to perform recursion?
- The data structure used for recursion is Stack.
- Its LIFO property helps it remembers its 'caller'. This helps it
know the data which is to be returned when the function has to return.
- System stack is used for storing the return addresses of the
function calls.
3. Does the Minimal Spanning tree of a graph give the shortest
distance between any 2 specified nodes?
- No, it doesn’t.
- It assures that the total weight of the tree is kept to minimum.
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- It doesn't imply that the distance between any two nodes involved in
the minimum-spanning tree is minimum.
4. If you are using C language to implement the heterogeneous linked
list, what pointer type will you use?
- A heterogeneous linked list contains different data types in its
nodes. We can not use ordinary pointer to connect them.
- The pointer that we use in such a case is void pointer as it is a
generic pointer type and capable of storing pointer to any type.
5. Differentiate between PUSH and POP?
- Pushing and popping refers to the way data is stored into and
retrieved from a stack.
- PUSH – Data being pushed/ added to the stack.
- POP - Data being retrieved from the stack, particularly the topmost
data.
6. When is a binary search algorithm best applied?
- It is best applied to search a list when the elements are already in
order or sorted.
- The list here is searched starting in the middle. If that middle
value is not the correct one, the lower or the upper half is searched
in the similar way.
7. How do you reference all the elements in a one-dimension array?
- This is done using an indexed loop.
- The counter runs from 0 to the array size minus one.
- Using the loop counter as the array subscript helps in referencing
all the elements in one-dimensional array.
8. What is Huffman’s algorithm?
- It is used in creating extended binary trees that have minimum
weighted path lengths from the given weights.
- It makes use of a table that contains frequency of occurrence for
each data element.
9. What is Fibonacci search?
- It is a search algorithm that applies to a sorted array.
- It uses divide-and-conquer approach that reduces the time needed to
reach the target element.
10. Which data structure is applied when dealing with a recursive
function?
- A recursive function is a function that calls itself based on a
terminating condition.
- It uses stack.
- Using LIFO, a call to a recursive function saves the return address.
This tells the return address to the calling function after the call
terminates.
11. How does dynamic memory allocation help in managing data?
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- Dynamic memory allocation helps to store simple structured data
types.
- It can combine separately allocated structured blocks to form
composite structures that expand and contract as required.
12. What is a bubble sort and how do you perform it?
- Bubble sort is a sorting technique which can be applied to data
structures like arrays.
- Here, the adjacent values are compared and their positions are
exchanged if they are out of order.
- The smaller value bubbles up to the top of the list, while the
larger value sinks to the bottom.
13. How does variable declaration affect memory allocation?
- The amount of memory to be allocated depends on the data type of the
variable.
- An integer type variable is needs 32 bits of memory storage to be
reserved.
14. You want to insert a new item in a binary search tree. How would
you do it?
- Let us assume that the you want to insert is unique.
- First of all, check if the tree is empty.
- If it is empty, you can insert the new item in the root node.
- If it is not empty, refer to the new item’s key.
- If the data to be entered is smaller than the root’s key, insert it
into the root’s left subtree.
- Otherwise, insert it into the root’s right subtree.
15. Why is the isEmpty() member method called?
- The isEmpty() member method is called during the dequeue process. It
helps in ascertaining if there exists any item in the queue which
needs to be removed.
- This method is called by the dequeue() method before returning the
front element.
16. What is a queue ?
- A Queue refers to a sequential organization of data.
- It is a FIFO type data structure in which an element is always
inserted at the last position and any element is always removed from
the first position.
17. What is adequeue?
- A dequeue is a double-ended queue.
- The elements here can be inserted or removed from either end.
18. What is a postfix expression?
- It is an expression in which each operator follows its operands.
- Here, there is no need to group sub-expressions in parentheses or to
consider operator precedence..
1.What is a data structure? What are the types of data structures?
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The scheme of organizing related information is known as ‘data
structure’. The types of data structure are: Lists: A group of similar
items with connectivity to the previous or/and next data item
2.Define a linear and non linear data structure.
Linear data structure: A linear data structure traverses the data
elements sequentially, in which only one data element can directly be
reached. Ex:
Arrays, Linked Lists...............
3.Define in brief an array. What are the types of array operations?
An array is a set of homogeneous elements. Every element is referred
by an index. Arrays are used for storing the data until the
application expires in the main memory of the computer system. So
that, the elements can be accessed at any time. The operations are:
4.What is a matrix? Explain its uses with an example
A matrix is a representation of certain rows and columns, to persist
homogeneous data. It can also be called as double-dimensioned
array.................
5.Define an algorithm. What are the properties of an algorithm? What
are the types of algorithms?
Algorithm: A step by step process to get the solution for a well
defined problem..............
6.What is an iterative algorithm?
The process of attempting for solving a problem which finds successive
approximations for solution, starting from an initial ..
7.What is an recursive algorithm?
Recursive algorithm is a method of simplification that divides the
problem into sub-problems of the same nature. The result of one
recursion is the input for the next recursion...............
8.What is the Huffman algorithm?
In Huffman Algorithm, a set of nodes assigned with values if fed to
the algorithm................
9.Explain quick sort and merge sort algorithms.
Quick sort employs the ‘divide and conquer’ concept by dividing the
list of elements into two sub elements............
9.What is Bubble Sort and Quick sort?
Bubble Sort: The simplest sorting algorithm. It involves the sorting
the list in a repetitive fashion. It compares two adjacent elements in
the list..............
10.What is the difference between a stack and a Queue?
11
Stack – Represents the collection of elements in Last In First Out
order.
Operations includes testing null stack, finding the top element in the
stack, removal of top most element and adding elements on the top of
the stack..............
11.Can a stack be described as a pointer? Explain
A stack is represented as a pointer. The reason is that, it has a head
pointer which points to the top of the stack..............
12.What is the recursion?
Recursion is an approach in which a function calls itself with an
argument. Upon reaching a termination condition, the control returns
to the calling function...............
13.Is it possible to insert different type of elements in a stack?
How?
Different elements can be inserted into a stack. This is possible by
implementing union / structure data type............
14.Explain in brief a linked list.
A linked list is a dynamic data structure. It consists of a sequence
of data elements and a reference to the next record in the sequence.
Stacks, queues, hash tables, linear equations, prefix and post fix
operations..................
15.Explain the types of linked lists.
The types of linked lists are:
Singly linked list: It has only head part and corresponding references
to the next nodes...............
16.How would you sort a linked list?
1: Compare the current node in the unsorted list with every element in
the rest of the list. If the current element is more than any other
element go to step 2 otherwise go to step 3..............
17.What is sequential search? What is the average number of
comparisons in a sequential search?
Sequential search: Searching an element in an array, the search starts
from the first element till the last element..............
18.What is binary searching and Fibonacci search?
Binary Search: Binary search is the process of locating an element in
a sorted list. The search starts by dividing the list into two
parts...............
19. What is a data structure? What are the types of data structures?
Briefly explain them
The scheme of organizing related information is known as ‘data
structure’. The types of data structure are:
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Lists: A group of similar items with connectivity to the previous
or/and next data items.
Arrays: A set of homogeneous values
Records: A set of fields, where each field consists of data belongs to
one data type.
Trees: A data structure where the data is organized in a hierarchical
structure. This type of data structure follows the sorted order of
insertion, deletion and modification of data items.
Tables: Data is persisted in the form of rows and columns. These are
similar to records, where the result or manipulation of data is
reflected for the whole table.
20. Define a linear and non linear data structure.
Linear data structure: A linear data structure traverses the data
elements sequentially, in which only one data element can directly be
reached. Ex: Arrays, Linked Lists
Non-Linear data structure: Every data item is attached to several
other data items in a way that is specific for reflecting
relationships. The data items are not arranged in a sequential
structure. Ex: Trees, Graphs
21. Define in brief an array. What are the types of array operations?
An array is a set of homogeneous elements. Every element is referred
by an index.
Arrays are used for storing the data until the application expires in
the main memory of the computer system. So that, the elements can be
accessed at any time. The operations are:
-
Adding elements
Sorting elements
Searching elements
Re-arranging the elements
Performing matrix operations
Pre-fix and post-fix operations
22. What is a matrix? Explain its uses with an example
A matrix is a representation of certain rows and columns, to persist
homogeneous data. It can also be called as double-dimensioned array.
Uses:
-
To represent class hierarchy using Boolean square matrix
For data encryption and decryption
To represent traffic flow and plumbing in a network
To implement graph theory of node representation
23. Define an algorithm. What are the properties of an algorithm? What
are the types of algorithms?
Algorithm: A step by step process to get the solution for a well
defined problem.
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Properties of an algorithm:
- Should be written in simple English
- Should be unambiguous, precise and lucid
- Should provide the correct solutions
- Should have an end point
- The output statements should follow input, process instructions
- The initial statements should be of input statements
- Should have finite number of steps
- Every statement should be definitive
Types of algorithms:
- Simple recursive algorithms. Ex: Searching an element in a list
– Backtracking algorithms Ex: Depth-first recursive search in a tree
– Divide and conquer algorithms. Ex: Quick sort and merge sort
– Dynamic programming algorithms. Ex: Generation of Fibonacci series
– Greedy algorithms Ex: Counting currency
– Branch and bound algorithms. Ex: Travelling salesman (visiting each
city once and minimize the total distance travelled)
– Brute force algorithms. Ex: Finding the best path for a travelling
salesman
– Randomized algorithms. Ex. Using a random number to choose a pivot
in quick sort).
24. What is an iterative algorithm?
The process of attempting for solving a problem which finds successive
approximations for solution, starting from an initial guess. The
result of repeated calculations is a sequence of approximate values
for the quantities of interest.
25. What is an recursive algorithm?
Recursive algorithm is a method of simplification that divides the
problem into sub-problems of the same nature. The result of one
recursion is the input for the next recursion. The repletion is in the
self-similar fashion. The algorithm calls itself with smaller input
values and obtains the results by simply performing the
operations on these smaller values. Generation of factorial, Fibonacci
number series are the examples of recursive algorithms.
26. Explain quick sort and merge sort algorithms.
Quick sort employs the ‘divide and conquer’ concept by dividing the
list of elements into two sub elements. The process is as follows:
1. Select an element, pivot, from the list.
2. Rearrange the elements in the list, so that all elements those are
less than the pivot are arranged before the pivot and all elements
those are greater than the pivot are arranged after the pivot. Now the
pivot is in its position.
3. Sort the both sub lists – sub list of the elements which are less
than the pivot and the list of elements which are more than the pivot
recursively.
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Merge Sort: A comparison based sorting algorithm. The input order is
preserved in the sorted output.
Merge Sort algorithm is as follows:
1. The length of the list is 0 or 1, and then it is considered as
sorted.
2. Other wise, divide the unsorted list into 2 lists each about half
the size.
3. Sort each sub list recursively. Implement the step 2 until the two
sub lists are sorted.
4. As a final step, combine (merge) both the lists back into one
sorted list.
27. What is Bubble Sort and Quick sort?
Bubble Sort: The simplest sorting algorithm. It involves the sorting
the list in a repetitive fashion. It compares two adjacent elements in
the list, and swaps them if they are not in the designated order. It
continues until there are no swaps needed. This is the signal for the
list that is sorted. It is also called as comparison sort as it uses
comparisons.
Quick Sort: The best sorting algorithm which implements the ‘divide
and conquer’ concept. It first divides the list into two parts by
picking an element a ’pivot’. It then arranges the elements those are
smaller than pivot into one sub list and the elements those are
greater than pivot into one sub list by keeping the pivot in its
original place.
28. What are the difference between a stack and a Queue?
Stack – Represents the collection of elements in Last In First Out
order. Operations includes testing null stack, finding the top element
in the stack, removal of top most element and adding elements on the
top of the stack.
Queue - Represents the collection of elements in First In First Out
order. Operations include testing null queue, finding the next
element, removal of elements and inserting the elements from the
queue.
Insertion of elements is at the end of the queue
Deletion of elements is from the beginning of the queue.
29. Can a stack be described as a pointer? Explain.
A stack is represented as a pointer. The reason is that, it has a head
pointer which points to the top of the stack. The stack operations are
performed using the head pointer. Hence, the stack can be described as
a pointer.
30. Explain the terms Base case, Recursive case, Binding Time, RunTime Stack and Tail Recursion.
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Base case: A case in recursion, in which the answer is known when the
termination for a recursive condition is to unwind back.
Recursive Case: A case which returns to the answer which is closer.
Run-time Stack: A run time stack used for saving the frame stack of a
function when every recursion or every call occurs.
Tail Recursion: It is a situation where a single recursive call is
consisted by a function, and it is the final statement to be executed.
It can be replaced by iteration.
31. Is it possible to insert different type of elements in a stack?
How?
Different elements can be inserted into a stack. This is possible by
implementing union / structure data type. It is efficient to use union
rather than structure, as only one item’s memory is used at a time.
32. Explain in brief a linked list.
A linked list is a dynamic data structure. It consists of a sequence
of data elements and a reference to the next record in the sequence.
Stacks, queues, hash tables, linear equations, prefix and post fix
operations. The order of linked items is different that of arrays. The
insertion or deletion operations are constant in number.
33. Explain the types of linked lists.
The types of linked lists are:
Singly linked list: It has only head part and corresponding references
to the next nodes.
Doubly linked list: A linked list which both head and tail parts, thus
allowing the traversal in bi-directional fashion. Except the first
node, the head node refers to the previous node.
Circular linked list: A linked list whose last node has reference to
the first node.
34. How would you sort a linked list?
Step 1: Compare the current node in the unsorted list with every
element in the rest of the list. If the current element is more than
any other element go to step 2 otherwise go to step 3.
Step 2: Position the element with higher value after the position of
the current element. Compare the next element. Go to step1 if an
element exists, else stop the process.
Step 3: If the list is already in sorted order, insert the current
node at the end of the list. Compare the next element, if any and go
to step 1 or quit.
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35. What is sequential search? What is the average number of
comparisons in a sequential search?
Sequential search: Searching an element in an array, the search starts
from the first element till the last element.
The average number of comparisons in a sequential search is (N+1)/2
where N is the size of the array. If the element is in the 1st
position, the number of comparisons will be 1 and if the element is in
the last position, the number of comparisons will be N.
36. What are binary search and Fibonacci search?
Binary Search: Binary search is the process of locating an element in
a sorted list. The search starts by dividing the list into two parts.
The algorithm compares the median value. If the search element is less
than the median value, the top list only will be searched, after
finding the middle element of that list. The process continues until
the element is found or the search in the top list is completed. The
same process is continued for the bottom list, until the element is
found or the search in the bottom list is completed. If an element is
found that must be the median value.
Fibonacci Search: Fibonacci search is a process of searching a sorted
array by utilizing divide and conquer algorithm. Fibonacci search
examines locations whose addresses have lower dispersion. When the
search element has non-uniform access memory storage, the Fibonacci
search algorithm reduces the average time needed for accessing a
storage location.
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) 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) 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.
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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.
5)What are the methods available in storing sequential files ?
Straight merging, Natural merging, Polyphase sort, Distribution of
Initial runs.
6) List out few of the Application of tree data-structure?
The manipulation of Arithmetic expression, Symbol Table construction,
Syntax analysis.
7) In RDBMS, what is the efficient data structure used in the internal
storage representation? 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.
8) 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.
9) Does the minimum spanning tree of a graph give the shortest
distance between any 2 specified nodes?
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.
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.
11) What is the quickest sorting method to use?
The answer depends on what you mean by quickest. For most sorting
problems, it just doesn't matter how quick the sort is because it is
done infrequently or other operations take significantly more time
anyway. Even in cases in which sorting speed is of the essence, there
is no one answer. It depends on not only the size and nature of the
data, but also the likely order. No algorithm is best in all cases.
There are three sorting methods in this author's toolbox that are all
very fast and that are useful in different situations. Those methods
are quick sort, merge sort, and radix sort.
The Quick Sort
The quick sort algorithm is of the divide and conquer type. That means
it works by reducing a sorting problem into several easier sorting
problems and solving each of them. A dividing value is chosen from the
input data, and the data is partitioned into three sets: elements that
belong before the dividing value, the value itself, and elements that
come after the dividing value. The partitioning is performed by
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exchanging elements that are in the first set but belong in the third
with elements that are in the third set but belong in the first
Elements that are equal to the dividing element can be put in any of
the three sets the algorithm will still work properly.
The Merge Sort
The merge sort is a divide and conquer sort as well. It works by
considering the data to be sorted as a sequence of already-sorted
lists (in the worst case, each list is one element long). Adjacent
sorted lists are merged into larger sorted lists until there is a
single sorted list containing all the elements. The merge sort is good
at sorting lists and other data structures that are not in arrays, and
it can be used to sort things that don't fit into memory. It also can
be implemented as a stable sort.
The Radix Sort
The radix sort takes a list of integers and puts each element on a
smaller list, depending on the value of its least significant byte.
Then the small lists are concatenated, and the process is repeated for
each more significant byte until the list is sorted. The radix sort is
simpler to implement on fixed-length data such as ints.
How can I search for data in a linked list?
Unfortunately, the only way to search a linked list is with a linear
search, because the only way a linked list's members can be accessed
is sequentially. Sometimes it is quicker to take the data from a
linked list and store it in a different data structure so that
searches can be more efficient.
12) What is the heap?
The heap is where malloc(), calloc(), and realloc() get memory.
13 )What is the easiest sorting method to use?
The answer is the standard library function qsort(). It's the easiest
sort by far for several reasons:
It is already written.
It is already debugged.
It has been optimized as much as possible (usually).
Void qsort(void *buf, size_t num, size_t size, int (*comp)(const void
*ele1, const void *ele2));
14) 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 an AVL tree, at what condition the balancing is to be done?
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If the pivotal value (or the Height factor) is greater than 1 or less
than 1.
16) 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.
17)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.
18) What is a node class?
A node class is a class that, relies on the base class for services
and implementation, provides a wider interface to users than its base
class, relies primarily on virtual functions in its public interface
depends on all its direct and indirect base class can be understood
only in the context of the base class can be used as base for further
derivation can be used to create objects. A node class is a class that
has added new services or functionality beyond the services inherited
from its base class.
19)When can you tell that a memory leak will occur?
A memory leak occurs when a program loses the ability to free a block
of dynamically allocated memory.
20) What is placement new?
When you want to call a constructor directly, you use the placement
new. Sometimes you have some raw memory that’s already been allocated,
and you need to construct an object in the memory you have. Operator
new’s special version placement new allows you to do it.
21)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
22)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.
23)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
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iterative (non-recursive) function. Even when such equivalent
iterative procedures are written, explicit stack is to be used.
24)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
25) What is the difference between ARRAY and STACK?
STACK follows LIFO. Thus the item that is first entered would be the
last removed.
In array the items can be entered or removed in any order. Basically
each member access is done using index. No strict order is to be
followed here to remove a particular element.
26) What is the difference between NULL AND VOID pointer?
NULL can be value for pointer type variables.
VOID is a type identifier which has not size.
NULL and void are not same. Example: void* ptr = NULL;
27) What is precision?
Precision refers the accuracy of the decimal portion of a value.
Precision is the number of digits allowed after the decimal point.
What is impact of signed numbers on the memory?
Sign of the number is the first bit of the storage allocated for that
number. So you get one bit less for storing the number. For example if
you are storing an 8-bit number, without sign, the range is 0-255. If
you decide to store sign you get 7 bits for the number plus one bit
for the sign. So the range is -128 to +127.
28)How memory is reserved using a declaration statement ?
Memory is reserved using data type in the variable declaration. A
programming language implementation has predefined sizes for its data
types.
For example, in C# the declaration int i; will reserve 32 bits for
variable i.
A pointer declaration reserves memory for the address or the pointer
variable, but not for the data that it will point to. The memory for
the data pointed by a pointer has to be allocated at runtime.
The memory reserved by the compiler for simple variables and for
storing pointer address is allocated on the stack, while the memory
allocated for pointer referenced data at runtime is allocated on the
heap.
29) How many parts are there in a declaration statement?
There are two main parts, variable identifier and data type and the
third type is optional which is type qualifier like signed/unsigned.
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30) Is Pointer a variable?
Yes, a pointer is a variable and can be used as an element of a
structure and as an attribute of a class in some programming languages
such as C++, but not Java.
However, the contents of a pointer is a memory address of another
location of memory, which is usually the memory address of another
variable, element of a structure, or attribute of a class.
31)What is Data Structure?
A data structure is a group of data elements grouped together under
one name. These data elements, known as members, can have different
types and different lengths.
Some are used to store the data of same type and some are used to
store different types of data.
32)What is significance of ” * ” ?
The symbol “*” tells the computer that you are declaring a pointer.
Actually it depends on context.
In a statement like int *ptr; the ‘*’ tells that you are declaring a
pointer.
In a statement like int i = *ptr; it tells that you want to assign
value pointed to by ptr to variable i.
The symbol “*” is also called as Indirection Operator/ Dereferencing
Operator.
33) Why do we Use a Multidimensional Array?
A multidimensional array can be useful to organize subgroups of data
within an array. In addition to organizing data stored in elements of
an array, a multidimensional array can store memory addresses of data
in a pointer array and an array of pointers.
Multidimensional arrays are used to store information in a matrix
form.
e.g. a railway timetable, schedule cannot be stored as a single
dimensional array.
One can use a 3-D array for storing height, width and length of each
room on each floor of a building.
34) How do you assign an address to an element of a pointer array ?
We can assign a memory address to an element of a pointer array by
using the address operator, which is the ampersand (&), in an
assignment statement such as
ptemployee[0] = &projects[2];
35)Run Time Memory Allocation is known as ?
Allocating memory at runtime is called a dynamically allocating
memory. In this, you dynamically allocate memory by using the new
operator when declaring the array,
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for example : int grades[] = new int[10];
36)What method is used to place a value onto the top of a stack?
push() method, Push is the direction that data is being added to the
stack. push() member method places a value onto the top of a stack.
37) What method removes the value from the top of a stack?
The pop() member method removes the value from the top of a stack,
which is then returned by the pop() member method to the statement
that calls the pop() member method.
38) What does isEmpty() member method determines?
isEmpty() checks if the stack has at least one element. This method is
called by Pop() before retrieving and returning the top element.
39) What is a queue ?
A Queue is a sequential organization of data. A queue is a first in
first out type of data structure. An element is inserted at the last
position and an element is always taken out from the first position.
What is the relationship between a queue and its underlying array?
Data stored in a queue is actually stored in an array. Two indexes,
front and end will be used to identify the start and end of the queue.
40) Why is the isEmpty() member method called?
The isEmpty() member method is called within the dequeue process to
determine if there is an item in the queue to be removed i.e.
isEmpty() is called to decide whether the queue has at least one
element. This method is called by the dequeue() method before
returning the front element.
41) How is the front of the queue calculated ?
The front of the queue is calculated by front = (front+1) % size.
42 )What does each entry in the Link List called?
Each entry in a linked list is called a node. Think of a node as an
entry that has three sub entries. One sub entry contains the data,
which may be one attribute or many attributes. Another points to the
previous node, and the last points to the next node. When you enter a
new item on a linked list, you allocate the new node and then set the
pointers to previous and next nodes.
43) What is Linked List ?
Linked List is one of the fundamental data structures. It consists of
a sequence of? nodes, each containing arbitrary data fields and one or
two (”links”) pointing to the next and/or previous nodes. A linked
list is a self-referential datatype because it contains a pointer or
link to another data of the same type. Linked lists permit insertion
and removal of nodes at any point in the list in constant time, but do
not allow random access.
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44) What member function places a new node at the end of the linked
list?
The appendNode() member function places a new node at the end of the
linked list. The appendNode() requires an integer representing the
current data of the node.
45 )How is any Data Structure application is classified among files?
A linked list application can be organized into a header file, source
file and main application file. The first file is the header file that
contains the definition of the NODE structure and the LinkedList class
definition. The second file is a source code file containing the
implementation of member functions of the LinkedList class. The last
file is the application file that contains code that creates and uses
the LinkedList class.
46) Which file contains the definition of member functions?
Definitions of member functions for the Linked List class are
contained in the LinkedList.cpp file.
What are the major data structures used in the following areas :
RDBMS, Network data model & Hierarchical data model.
1. RDBMS Array (i.e. Array of structures)
2. Network data model Graph
3. Hierarchical data model Trees.
47 ) Difference between calloc and malloc ?
malloc: allocate n bytes
calloc: allocate m times n bytes initialized to 0
1.
What is data structure?
The logical and mathematical model of a particular organization of
data is called data structure.
There are two types of data structure
Linear
Nonlinear
2.
What is a linked list?
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.
3.
What is a queue?
A queue is an ordered collection of items from which items may be
deleted at one end (front end) and items inserted at the other end
(rear end). It obeys FIFO rule there is no limit to the number of
elements a queue contains.
4.
What is a spanning Tree?
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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.
5.
What is precision?
Precision refers the accuracy of the decimal portion of a value.
Precision is the number of digits allowed after the decimal point.
6.
What are the goals of Data Structure?
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.
7.
What is the difference between a Stack and an Array?
Stack
Stack is a dynamic object whose size is constantly changing as
items are pushed and popped .
Stack may contain different data types.
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.
Stack is a ordered collection of items.
Array
Array is an ordered collection of items.
Array is a static object.
It contains same data types.
Array can be home of a stack i.e. array can be declared large
enough for maximum size of the stack.
8.
What is sequential search?
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.
9.
What are the disadvantages array implementations of linked list?
The no of nodes needed can’t be predicted when the program is written.
The no of nodes declared must remain allocated throughout its
execution.
10. What is a priority queue?
The priority queue is a data structure in which the intrinsic ordering
of the elements.
11. What are the disadvantages of sequential storage?
Fixed amount of storage remains allocated to the data structure even
if it contains less element.No more than fixed amount of storage is
allocated causing overflow.
12.
Define circular list?
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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.
13. What does abstract Data Type Mean?
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.
14. What do you mean by recursive definition?
The definition which defines an object in terms of simpler cases of
itself is called recursive definition.
15.
What actions are performed when a function is called?
When a function is called arguments are passed local variables are
allocated and initialized transferring control to the function
16. Define double linked list?
It is a collection of data elements called nodes, where each node is
divided into three parts
An info field that contains the information stored in the node.
Left field that contain pointer to node on left side.
Right field that contain pointer to node on right side.
17. What do you mean by overflow and underflow?
When new data is to be inserted into the data structure but there is
no available space i.e.free storage list is empty this situation is
called overflow.
When we want to delete data from a data structure that is empty this
situation is called underflow.
18. 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.
19. What do you mean by free pool?
Pool is a list consisting of unused memory cells which has its own
pointer.
20.
What are the methods available in storing sequential files ?
Straight merging
Natural merging
Polyphase sort
Distribution of Initial runs
21. What is a node class?
A node class is a class that has added new services or functionality
beyond the services inherited from its base class.
22.
what is binary tree?
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A binary tree is a tree data structure in which each node has at most
two child nodes, usually distinguished as left and right.
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