7 Must Know Data Structures | Popular Data Structures | Data Structures Explained | Coding Interview

In this video we are going to discuss 7 essential and very popular data structures. These are part of almost every technical interview that you give for a software developer position and questions will directly or indirectly use one of these data structures. I am also going to talk about complexity analysis for various operations for each of these data structures at the end.

• Array is a linear data structure. It is a collection of items stored at contiguous memory locations. The idea is to store multiple items of the same type together in one place. Array elements are accessed using index. There are different operations possible in an array, like Searching, Sorting, Inserting, Traversing, Reversing, and Deleting. An array is also used to implement other data structures like Stacks, Queues, Heaps, Hash tables, etc.
• Linked list is a linear data structure in which elements are not stored at contiguous memory locations. The elements are called nodes. And nodes in a linked list are linked using pointers. Thus, each node has 2 attributes - data and next pointer to the next node. Linked lists are used to implement stacks, queues, graphs, etc. There are various types of linked list like Singly-linked list, Doubly linked list, Circular linked list, Doubly circular linked list.
• Stack is a linear data structure containing the top and bottom of the stack. It follows a particular order in which the operations are performed. When an element is inserted its called Push and when an element is deleted its called Pop. Insertion and deletion happens at the same end in a stack data structure. It follow LIFO i.e. Last-in, first-out order. So if you want to remove an element from the middle of the stack, you have to first remove all elements on top of it from the stack. Stack data structure is used in evaluation and conversion of arithmetic expressions. Stack is used in Recursion. It is used for parenthesis checking.
• Queue is a linear data structure which has Rear and Front end. It follows a particular order in which the operations are performed where inserting an element is called Enqueue and deleting an element is called Dequeue. Queues are used to maintain playlists in media players, job scheduling in operating systems, when sending an email. A more real-world example can be seen in the queue at the ticket window counters, person joining the queue at the first will move out of the queue also first.
• Hashing is a technique or process of mapping keys, and values into the hash table. Each key/value pair is called a record. The mapping of keys and values happens by using a hash function to compute an index, also called a hash code. It is done for faster access to elements. The efficiency of mapping depends on the efficiency of the hash function used. Hashing is used in several real-world applications like database indexing, caches.
• Tree is a non-linear and hierarchal data structure where the elements are arranged in a tree-like structure. In a tree, each node contains some data, and data can be of any type. The topmost node is called the root node. Two nodes directly connected as children to the same node are called siblings. The nodes at the bottom which don’t have any other children are called leaf nodes. Every tree has multiple levels. The longest path from the root node to a leaf node is called the height of the tree. Tree data structures are used in various Game development, Domain Name Server also uses tree data structure.
• Graph is a non-linear data structure that consists of vertices (or nodes) and edges. It consists of a finite set of vertices and set of edges that connect a pair of nodes. Some graphs can also contain self loops. Graphs are used in social network sites where every person is a vertex and all friendships are edges which form the entire network. Graphs are also used in Maps like Google maps where every place is a vertex and paths connecting those are edges.

*TABLE OF CONTENTS - 7 Popular Data Structures | Array, Linked List, Stack, Queue, Hashing, Tree, Graph | with Complexity*
• 00:00 Introduction
• 00:36 Array Data Structure
• 01:37 Linked List Data Structure
• 02:43 Stack Data Structure
• 03:56 Queue Data Structure
• 05:31 Hash Table Data Structure
• 06:55 Tree Data Structure
• 08:41 Graph Data Structure

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[pooja]

Very informational ! Really liked the tree data structure explanation.

[SumanAmara]

Nice explanation I am waiting for this kind of short explanation because in the normal world you will not use all these things can you please elaborate one by one if already done plz share

[aliciagolden]

This was a really great video!!! I think you will be interested in "Promo sm".