Technical interview questions and answers are the foundation of any Data Structure Interview because companies use DSA to test your problem-solving ability, logic building, and coding efficiency. Data Structures such as arrays, linked lists, stacks, queues, trees, and graphs form the backbone of programming, making this topic one of the most important parts of technical rounds. In campus placements and company-specific interviews conducted by TCS, Infosys, Wipro, Cognizant, and Capgemini, these questions decide whether a candidate has strong fundamentals. This guide covers the most important and frequently asked Data Structure interview questions with clear explanations, helping freshers and job seekers understand concepts easily. Preparing these questions improves performance in coding tests, whiteboard interviews, and online assessments.
Computer science professionals should complement their algorithmic knowledge with C language implementation and Java programming techniques
Showing 10 of 108 questions
1. Calculate the efficiency of sequential search?
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).
2. Can we apply binary search algorithm to a sorted linked list, why?
No we cannot apply binary search algorithm to a sorted linked list, since there is no way of indexing the middle element in the list. This is the drawback in using linked list as a data structure.
3. Convert the expression ((A + B) * C - (D - E) ^ (F + G)) to equivalent Prefix and Postfix notations.
Prefix Notation:
^ - * +ABC - DE + FG
Postfix Notation:
AB + C * DE - - FG + ^
4. Define circular list?
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
5. Define double linked list?
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
6. Does the minimum spanning tree of a graph give the shortest distance between any 2 specified nodes?
No Minimal spanning tree assures that the total weight of the tree is kept at its minimum. But it does not mean that the distance between any two nodes involved in the minimum-spanning tree is minimum.
7. 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.
8. 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.
9. 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.
10. Is any implicit arguments are passed to a function when it is called?
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 is data area, at the time of returning to calling program the address is retrieved and the function branches to that location.