Update Basic-DSA

Author: Shrutigupta03

Basic-DSA

@@ -1,10 +1,96 @@
+Data Structure is a systematic way to organize data in order to use it efficiently. Following terms are the foundation terms of a data structure.
+
+Interface − Each data structure has an interface. Interface represents the set of operations that a data structure supports. An interface only provides the list of supported operations, type of parameters they can accept and return type of these operations.
+
+Implementation − Implementation provides the internal representation of a data structure. Implementation also provides the definition of the algorithms used in the operations of the data structure.
+
+Characteristics of a Data Structure
+Correctness − Data structure implementation should implement its interface correctly.
+
+Time Complexity − Running time or the execution time of operations of data structure must be as small as possible.
+
+Space Complexity − Memory usage of a data structure operation should be as little as possible.
+
+Need for Data Structure
+As applications are getting complex and data rich, there are three common problems that applications face now-a-days.
+
+Data Search − Consider an inventory of 1 million(106) items of a store. If the application is to search an item, it has to search an item in 1 million(106) items every time slowing down the search. As data grows, search will become slower.
+
+Processor speed − Processor speed although being very high, falls limited if the data grows to billion records.
+
+Multiple requests − As thousands of users can search data simultaneously on a web server, even the fast server fails while searching the data.
+
+To solve the above-mentioned problems, data structures come to rescue. Data can be organized in a data structure in such a way that all items may not be required to be searched, and the required data can be searched almost instantly.
+
+Execution Time Cases
+There are three cases which are usually used to compare various data structure's execution time in a relative manner.
+
+Worst Case − This is the scenario where a particular data structure operation takes maximum time it can take. If an operation's worst case time is ƒ(n) then this operation will not take more than ƒ(n) time where ƒ(n) represents function of n.
+
+Average Case − This is the scenario depicting the average execution time of an operation of a data structure. If an operation takes ƒ(n) time in execution, then m operations will take mƒ(n) time.
+
+Best Case − This is the scenario depicting the least possible execution time of an operation of a data structure. If an operation takes ƒ(n) time in execution, then the actual operation may take time as the random number which would be maximum as ƒ(n).
+
+Basic Terminology
+Data − Data are values or set of values.
+
+Data Item − Data item refers to single unit of values.
+
+Group Items − Data items that are divided into sub items are called as Group Items.
+
+Elementary Items − Data items that cannot be divided are called as Elementary Items.
+
+Attribute and Entity − An entity is that which contains certain attributes or properties, which may be assigned values.
+
+Entity Set − Entities of similar attributes form an entity set.
+
+Field − Field is a single elementary unit of information representing an attribute of an entity.
+
+Record − Record is a collection of field values of a given entity.
+
+File − File is a collection of records of the entities in a given entity set.
+
+
+Data Definition
+Data Definition defines a particular data with the following characteristics.
+
+Atomic − Definition should define a single concept.
+
+Traceable − Definition should be able to be mapped to some data element.
+
+Accurate − Definition should be unambiguous.
+
+Clear and Concise − Definition should be understandable.
+
+Data Object
+Data Object represents an object having a data.
+
+Data Type
+Data type is a way to classify various types of data such as integer, string, etc. which determines the values that can be used with the corresponding type of data, the type of operations that can be performed on the corresponding type of data. There are two data types −
+
+Built-in Data Type
 Derived Data Type
-Those data types which are implementation independent as they can be implemented in one or other way are known as derived data types. These data types are normally built by combination of primary or built-in data types and associated operations on them. For example −
+Built-in Data Type
+Those data types for which a language has built-in support are known as Built-in Data types. For example, most of the languages provide the following built-in data types.
 
-List
+Integers
+Boolean (true, false)
+Floating (Decimal numbers)
+Character and Strings
+Derived Data Type
+Those data types which are implementation independent as they can be implemented in one or the other way are known as derived data types. These data types are normally built by the combination of primary or built-in data types and associated operations on them. For example −
 
+List
 Array
-
 Stack
-
 Queue
+
+Basic Operations
+The data in the data structures are processed by certain operations. The particular data structure chosen largely depends on the frequency of the operation that needs to be performed on the data structure.
+
+Traversing
+Searching
+Insertion
+Deletion
+Sorting
+Merging