Data Structure Interview Questions

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 sets of data and how they can relate to one another in an organized manner.

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 a file structure.

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.

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.

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.

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.

LIFO is a short form of Last In First Out. It refers to 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 to gain access to the first data, all the other data that was stored before this first data must first be retrieved and extracted.

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.

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.

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.

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.

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 node’s key value, while the right subtree contains nodes whose keys are greater than or equal to the node’s key value. Moreover, both subtrees are also binary search trees.

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.

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.

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.

An ordered list is a list in which each node’s 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.

Shell sort can be said a variant of insertion sort. Shell sort divides the list into smaller sublists based on some gap variable and then each sub-list is sorted using insertion sort. In best cases, it can perform up to ?(n log n).

Quicksort uses the divide and conquer approach. It divides the list into smaller partitions using pivot. The values which are smaller than the pivot are arranged in the left partition and greater values are arranged in the right partition. Each partition is recursively sorted using quicksort.

A graph is a pictorial representation of a set of objects where some pairs of objects are connected by links. The interconnected objects are represented by points termed as vertices, and the links that connect the vertices are called edges.

Depth First Search algorithm(DFS) traverses a graph in a deathward motion and uses a stack to remember to get the next vertex to start a search when a dead end occurs in any iteration.

Breadth-First Search algorithm(BFS) traverses a graph in a breadthwards motion and uses a queue to remember to get the next vertex to start a search when a dead end occurs in any iteration.

A tree is a minimally connected graph having no loops and circuits.

A binary tree has a special condition that each node can have two children at maximum.

A binary search tree is a binary tree with a special provision where a nodes left child must have a value less than its parents value and a nodes right child must have a value greater than its parent value.

AVL trees are height-balancing binary search trees. AVL tree checks the height of left and right sub-trees and assures that the difference is not more than 1. This difference is called Balance Factor.

BalanceFactor = height(left-sutree) ? height(right-sutree)

A spanning tree is a subset of Graph G, which has all the vertices covered with the minimum possible number of edges. A spanning tree does not have cycles and it can not be disconnected.

It depends on how connected the graph is. A complete undirected graph can have a maximum n^n-1 number of spanning trees, where n is several nodes.

This algorithm treats the graph as a forest and every node as an individual tree. A tree connects to another only and only if it has the least cost among all available options and does not violate MST properties.

Prims algorithm treats the nodes as a single tree and keeps on adding new nodes to the spanning tree from the given graph.

In a weighted graph, a minimum spanning tree is a spanning tree that has a minimum weight that all other spanning trees of the same graph.