Data Structure Questions
What is Fibonacci search?
Fibonacci search is a search algorithm that applies to a sorted array. It makes use of a divide-and-conquer approach that can significantly reduce the time needed in order to reach the target element.
What is Infix notation?
Infix notation: X + Y - Operators are written in-between their operands. This is the usual way we write expressions. An expression such as A * ( B + C ) / D
What are the various operations that can be performed on different Data Structures?
Insertion, Deletion, Traversal, Searching, Sorting.
What is inorder, preorder, and postorder of this BST?
(a) Inorder (Left, Root, Right): 4 2 5 1 3 (b) Preorder (Root, Left, Right): 1 2 4 5 3 (c) Postorder (Left, Right, Root): 4 5 2 3 1 Breadth First or Level Order Traversal : 1 2 3 4 5
What is the difference between a Singly Linked List and a Doubly Linked List?
A singly linked list is a set of nodes where each node has two fields 'data' and 'link'. The 'data' field stores actual piece of information and 'link' field is used to point to next node. Basically 'link' field is nothing but address only. A DLL contains an extra pointer, typically called previous pointer, together with next pointer and data which are there in singly linked list.
What is Data abstraction?
Data abstraction is a powerful tool for breaking down complex data problems into manageable chunks. This is applied by initially specifying the data objects involved and the operations to be performed on these data objects without being overly concerned with how the data objects will be represented and stored in memory.
Can doubly linked be implemented using a single pointer variable in every node?
Doubly linked list can be implemented using a single pointer. See XOR Linked List - A Memory Efficient Doubly Linked List
How to check if a given Binary Tree is BST or not?
If inorder traversal of a binary tree is sorted, then the binary tree is BST. The idea is to simply do inorder traversal and while traversing keep track of previous key value. If current key value is greater, then continue, else return false.
Are linked lists considered linear or non-linear data structures?
It depends on where you intend to apply linked lists. If you based it on storage, a linked list is considered non-linear. On the other hand, if you based it on access strategies, then a linked list is considered linear.
What are linear and non linear data Structures?
Linear: A data structure is said to be linear if its elements form a sequence or a linear list. Examples: Array. Linked List, Stacks and Queues Non-Linear: A data structure is said to be non-linear if traversal of nodes is nonlinear in nature. Example: Graph and Trees.
What are multidimensional arrays?
Multidimensional arrays make use of multiple indexes to store data. It is useful when storing data that cannot be represented using single dimensional indexing, such as data representation in a board game, tables with data stored in more than one column.
In what data structures are pointers applied?
Pointers that are used in linked list have various applications in the data structure. Data structures that make use of this concept include the Stack, Queue, Linked List and Binary Tree.
What is postfix notation?
Postfix notation (also known as "Reverse Polish notation"): X Y + Operators are written after their operands. The infix expression given above is equivalent to A B C + * D/
What is prefix notation?
Prefix notation (also known as "Polish notation"): + X Y Operators are written before their operands. The expressions given above are equivalent to / * A + B C D
Which data structures are used for BFS and DFS of a graph?
Queue is used for BFS Stack is used for DFS. DFS can also be implemented using recursion (Note that recursion also uses function call stack).
What is a Linked List and What are its types?
Singly Linked List : In this type of linked list, every node stores address or reference of next node in list and the last node has next address or reference as NULL. For example 1->2->3->4->NULL Doubly Linked List : Here, here are two references associated with each node, One of the reference points to the next node and one to the previous node. Eg. NULL<-1<->2<->3->NULL Circular Linked List : Circular linked list is a linked list where all nodes are connected to form a circle. There is no NULL at the end. A circular linked list can be a singly circular linked list or doubly circular linked list. Eg. 1->2->3->1 [The next pointer of last node is pointing to the first]
Differentiate linear from a nonlinear data structure.
The linear data structure is a structure wherein data elements are adjacent to each other. Examples of linear data structure include arrays, linked lists, stacks, and queues. On the other hand, a non-linear data structure is a structure wherein each data element can connect to more than two adjacent data elements. Examples of nonlinear data structure include trees and graphs.
How do you search for a target key in a linked list?
To find the target key in a linked list, you have to apply sequential search. Each node is traversed and compared with the target key, and if it is different, then it follows the link to the next node. This traversal continues until either the target key is found or if the last node is reached.
What are ARRAYs?
When dealing with arrays, data is stored and retrieved using an index that refers to the element number in the data sequence. This means that data can be accessed in any order. In programming, an array is declared as a variable having a number of indexed elements.
What is Stack and where it can be used?
Stack is a linear data structure which the order LIFO(Last In First Out) or FILO(First In Last Out) for accessing elements. Basic operations of stack are : Push, Pop , Peek
How to implement a queue using stack?
A queue can be implemented using two stacks. Let queue to be implemented be q and stacks used to implement q be stack1 and stack2. q can be implemented in two ways: Method 1 (By making enQueue operation costly) Method 2 (By making deQueue operation costly)
When is a binary search best applied?
A binary search is an algorithm that is best applied to search a list when the elements are already in order or sorted. The list is searched starting in the middle, such that if that middle value is not the target search key, it will check to see if it will continue the search on the lower half of the list or the higher half. The split and search will then continue in the same manner.
What is the minimum number of nodes that a binary tree can have?
A binary tree can have a minimum of zero nodes, which occurs when the nodes have NULL values. Furthermore, a binary tree can also have 1 or 2 nodes.
What are binary trees?
A binary tree is one type of data structure that has two nodes, a left node, and a right node. In programming, binary trees are an extension of the linked list structures.
What is a Data Structure?
A data structure is a way of organizing the data so that the data can be used efficiently. Different kinds of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks.
How to implement a stack using queue?
A stack can be implemented using two queues. Let stack to be implemented be 's' and queues used to implement be 'q1' and 'q2'. Stack 's' can be implemented in two ways: Method 1 (By making push operation costly) Method 2 (By making pop operation costly) See Implement Stack using Queues
How do you insert a new item in a binary search tree?
Assuming that the data to be inserted is a unique value (that is, not an existing entry in the tree), check first if the tree is empty. If it's empty, just insert the new item in the root node. If it's not empty, refer to the new item's key. If it's smaller than the root's key, insert it into the root's left subtree, otherwise, insert it into the root's right subtree.
What are dynamic data structures?
Dynamic data structures are structures that expand and contract as a program runs. It provides a flexible means of manipulating data because it can adjust according to the size of the data.
Which data structures are applied when dealing with a recursive function?
Recursion, is a function that calls itself based on a terminating condition, makes use of the stack. Using LIFO, a call to a recursive function saves the return address so that it knows how to return to the calling function after the call terminates.
Briefly explain recursive algorithm.
Recursive algorithm targets a problem by dividing it into smaller, manageable sub-problems. The output of one recursion after processing one sub-problem becomes the input to the next recursive process.
What is a Queue, how it is different from stack and how is it implemented?
Queue is a linear structure which follows the order is First In First Out (FIFO) to access elements. Mainly the following are basic operations on queue: Enqueue, Dequeue, Front, Rear The difference between stacks and queues is in removing. In a stack we remove the item the most recently added; in a queue, we remove the item the least recently added. Both Queues and Stacks can be implemented using Arrays and Linked Lists.
What is the minimum number of queues needed when implementing a priority queue?
The minimum number of queues needed in this case is two. One queue is intended for sorting priorities while the other queue is used for actual storage of data.
How is an Array different from Linked List?
The size of the arrays is fixed, Linked Lists are Dynamic in size. Inserting and deleting a new element in an array of elements is expensive, Whereas both insertion and deletion can easily be done in Linked Lists. Random access is not allowed in Linked Listed. Extra memory space for a pointer is required with each element of the Linked list. Arrays have better cache locality that can make a pretty big difference in performance.
Which sorting algorithm is considered the fastest?
There are many types of sorting algorithms: quick sort, bubble sort, balloon sort, radix sort, merge sort, etc. Not one can be considered the fastest because each algorithm is designed for a particular data structure and data set. It would depend on the data set that you would want to sort.
What is the primary advantage of a linked list?
A linked list is an ideal data structure because it can be modified easily. This means that editing a linked list works regardless of how many elements are in the list.
What are the parts of a linked list?
A linked list typically has two parts: the head and the tail. Between the head and tail lie the actual nodes. All these nodes are linked sequentially.
Which Data Structure Should be used for implementiong LRU cache?
We use two data structures to implement an LRU Cache. Queue which is implemented using a doubly linked list. The maximum size of the queue will be equal to the total number of frames available (cache size).The most recently used pages will be near rear end and least recently pages will be near front end. A Hash with page number as key and address of the corresponding queue node as value.
