Top 30 Data Structures Interview Questions & Answers:-
π» Preparing for a data analytics role? Donβt overlook Data Structures! π.Checkout Top 30 Top 30 Data Structures Interview Questions & Answers
Hereβs a list of key interview questions to ace your preparation:
βοΈ Arrays, Linked Lists, and Hashmaps β how and when to use them?
βοΈ Sorting and Searching Algorithms β can you optimize them?
βοΈ Trees and Graphs β understand traversal techniques.
βοΈ Stacks and Queues β know their applications.
Mastering these will boost your problem-solving skills and impress recruiters!
π
1) What is data structure?
Answer – Data structure refers to the way data is organized and manipulated. It seeks to find ways to make data access more efficient. When dealing with the data structure, we not only focus on one piece of data but the different set of data and how they can relate to one another in an organized manner.
2) Differentiate between file and structure storage structure.
Answer – The key difference between both the data structure is the memory area that is being accessed. When dealing with the structure that resides the main memory of the computer system, this is referred to as storage structure. When dealing with an auxiliary structure, we refer to it as file structures.
3) When is a binary search best applied?
Answer – 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.
4) What is a linked list?
Answer – A linked list is a sequence of nodes in which each node is connected to the node following it. This forms a chain-like link for data storage.
5) How do you reference all the elements in a one-dimension array?
Answer – To reference all the elements in a one-dimension array, you need to use an indexed loop so that, the counter runs from 0 to the array size minus one. In this manner, You can reference all . The elements in sequence by using the loop counter as the array subscript.
6) In what areas do data structures are applied?
Answer – Data structures are essential in almost every aspect where data is involved. In general, algorithms that involve efficient data structure is applied in the following areas: numerical analysis, operating system, A.I., compiler design, database management, graphics, and statistical analysis, to name a few.
7) What is LIFO?
Answer – LIFO is a short form of Last In First Out. It refers how data is accessed, stored and retrieved. Using this scheme, data that was stored last should be the one to be extracted first. This also means that in order to gain access to the first data, all the other data that was stored before this first data must first be retrieved and extracted.
8) What is a queue?
Answer – A queue is a data structure that can simulate a list or stream of data. In this structure, new elements are inserted at one end, and existing elements are removed from the other end.
9) What are binary trees?
Answer – 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.
10) Which data structures are applied when dealing with a recursive function?
Answer – 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.
11) What is a stack?
Answer – A stack is a data structure in which only the top element can be accessed. As data is stored in the stack, each data is pushed downward, leaving the most recently added data on top.
12) Explain Binary Search Tree
Answer – A binary search tree stores data in such a way that they can be retrieved very efficiently. The left subtree contains nodes whose keys are less than the nodeβs key value, while the right subtree contains nodes whose keys are greater than or equal to the nodeβs key value. Moreover, both subtrees are also binary search trees.
13) What are multidimensional arrays?
Answer – 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.
14) Are linked lists considered linear or non-linear data structures?
Answer – 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.
15) How does dynamic memory allocation help in managing data?
Answer – Apart from being able to store simple structured data types, dynamic memory allocation can combine separately allocated structured blocks to form composite structures that expand and contract as needed.
16) What is FIFO?
Answer – FIFO stands for First-in, First-out, and is used to represent how data is accessed in a queue. Data has been inserted into the queue list the longest is the one that is removed first
17) What is an ordered list?
Answer– An ordered list is a list in which each nodeβs position in the list is determined by the value of its key component, so that the key values form an increasing sequence, as the list is traversed.
18) What is merge sort?
Answer– Merge sort, is a divide-and-conquer approach for sorting the data. In a sequence of data, adjacent ones are merged and sorted to create bigger sorted lists. These sorted lists are then merged again to form an even bigger sorted list, which continues until you have one single sorted list.
19) Differentiate NULL and VOID
Answer – Null is a value, whereas Void is a data type identifier. A variable that is given a Null value indicates an empty value. The vold is used to identify pointers as having no initial size
20) What is the primary advantage of a linked list?
Answer – 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.
21) What is the difference between a PUSH and a POP?
Answer – Pushing and popping applies to the way data is stored and retrieved in a stack. A push denotes. Data being added to it, meaning data is being βpushedβ into the stack. On the other hand, a pop denotes data retrieval, and in particular, refers to the topmost data being accessed.
22) What is a linear search?
Answer – A linear search refers to the way a target key is being searched in a sequential data structure. In this method, each element in the list is checked and compared against the target key. The process is repeated until found or if the end of the file has been reached.
23) How does variable declaration affect memory allocation?
Answer – The amount of memory to be allocated or reserved would depend on the data type of the variable being declared. For example, if a variable is declared to be of integer type, then 32 bits of memory storage will be reserved for that variable.
24) What is the advantage of the heap over a stack?
Answer – The heap is more flexible than the stack. Thatβs because memory space for the heap can be dynamically allocated and de-allocated as needed. However, the memory of the heap can at times be slower when compared to that stack.
25) What is a postfix expression?
Answer – A postfix expression is an expression in which each operator follows its operands. The advantage of this form is that there is no need to group sub-expressions in parentheses or to consider operator precedence.
26) What is Data abstraction?
Answer – 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.
27) How do you insert a new item in a binary search tree?
Answer – 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 itβs empty, just insert the new item in the root node. If itβs not empty, refer to the new itemβs key. If itβs smaller than the rootβs key, insert it into the rootβs left subtree, otherwise, insert it into the rootβs right subtree.
28) How does a selection sort work for an array?
Answer – The selection sort is a fairly intuitive sorting algorithm, though not necessarily efficient. In this process, the smallest element is first located and switched with the element at subscript zero, The smallest element remaining in the subarray is then located next to subscripts 1 through n-1 and switched with the element at subscript 1, thereby placing the second smallest element in the second position. The steps are repeated in the same manner till the last element.
29) How do signed and unsigned numbers affect memory?
Answer – In the case of signed numbers, the first bit is used to indicate whether positive or negative, which leaves you with one bit short. With unsigned numbers, you have all bits available for that number. The effect is best seen in the number range (an unsigned 8-bit number has a range 0-255, while the 8-bit signed number has a range-128 to +127.
30) What is the minimum number of nodes that a binary tree can have?
Answer – 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.
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