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Vertex Cover of a Graph is to find a set of vertices V, such that for every edge connecting M to N in graph, either M or N (or both) are present in V. In this program, we Implement a Heuristic to Find the Vertex Cover of a Graph.AlgorithmBegin 1) Initialize a set S as empty. 2) Take an edge E of the connecting graph Say M and N. 3) Add both vertex to the set S. 4) Discard all edges in the graph with endpoints at M or N. 5) If some edge is ... Read More
You can use $indexOfArray operator for this. Let us create a collection with documents −>db.getIndexDemo.insertOne({"InstructorName":"Chris", "InstructorSubject":["MongoDB", "MySQL", "Java", "C++"]}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd5251de8cc557214c0df8") }Display all documents from a collection with the help of find() method −> db.getIndexDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cbd5251de8cc557214c0df8"), "InstructorName" : "Chris", "InstructorSubject" : [ "MongoDB", "MySQL", "Java", "C++" ] }Following is the query to get index of given element in an array field in MongoDB −> db.getIndexDemo.aggregate( [ { "$project": { ... Read More
A duplicate buffer of a buffer can be created using the method duplicate() in the class java.nio.ByteBuffer. This duplicate buffer is identical to the original buffer. The method duplicate() returns the duplicate buffer that was created.A program that demonstrates this is given as follows −Example Live Demoimport java.nio.*; import java.util.*; public class Demo { public static void main(String[] args) { int n = 5; try { ByteBuffer buffer1 = ByteBuffer.allocate(5); buffer1.put((byte)1); buffer1.put((byte)2); buffer1.put((byte)3); buffer1.put((byte)4); ... Read More
The duration can be obtained in a one millisecond format using the ofMillis() method in the Duration class in Java. This method requires a single parameter i.e. the number of milliseconds and it returns the duration in a one millisecond format. If the capacity of the duration is exceeded, then the ArithmeticException is thrown.A program that demonstrates this is given as follows −Example Live Demoimport java.time.Duration; public class Demo { public static void main(String[] args) { long milliseconds = 1000; Duration duration = Duration.ofMillis(milliseconds); ... Read More
The setAt0() method is used to set the Triplet value in JavaTuples and a copy with new value at the specified index i.e. index 0 here.Let us first see what we need to work with JavaTuples. To work with Triplet class in JavaTuples, you need to import the following package −import org.javatuples.Triplet;Note − Steps to download and run JavaTuples program If you are using Eclipse IDE to run Triplet Class in JavaTuples, then Right Click Project → Properties → Java Build Path → Add External Jars and upload the downloaded JavaTuples jar file.The following is an example −Exampleimport org.javatuples.Triplet; public ... Read More
For this, use the substring_index() function.The syntax is as followsselect substring_index(yourColumnName, '. ', -1) AS anyAliasNamefrom yourTableName;Let us first create a table. The query to create a table is as followsmysql> create table AllFiles - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > UserName varchar(10), - > FileName varchar(100) - > ); Query OK, 0 rows affected (0.65 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into AllFiles(UserName, FileName) values('Larry', 'AddTwoNumber.java'); Query OK, 1 ... Read More
The JSTL tags can be classified, according to their functions, into the following JSTL tag library groups that can be used when creating a JSP page −Core TagsFormatting tagsSQL tagsXML tagsJSTL Functions
An immutable copy of a instant where a time unit is subtracted from it can be obtained using the minus() method in the Instant class in Java. This method requires two parameters i.e. time to be subtracted from the instant and the unit in which it is to be subtracted. It also returns the immutable copy of the instant where the required time unit is subtracted.A program that demonstrates this is given as follows −Example Live Demoimport java.time.*; import java.time.temporal.ChronoUnit; public class Demo { public static void main(String[] args) { Instant i ... Read More
One of the best frameworks for developing crawlers is scrapy. Scrapy is a popular web scraping and crawling framework utilizing high-level functionality to make scraping websites easier.Installation Installing scrapy in windows is easy: we can use either pip or conda(if you have anaconda). Scrapy runs on both python 2 and 3 versions.pip install ScrapyOrconda install –c conda-forge scrapyIf Scrapy is installed correctly, a scrapy command will now be available in the terminal −C:\Users\rajesh>scrapy Scrapy 1.6.0 - no active project Usage: scrapy [options] [args] Available commands: bench Run quick benchmark test fetch Fetch a URL using the ... Read More
If you want to list all collections from a particular database then you need to switch the database first. The query is as follows −> use sample; switched to db sample > db.getCollectionNames();The following is the output −[ "copyThisCollectionToSampleDatabaseDemo", "deleteDocuments", "deleteDocumentsDemo", "deleteInformation", "employee", "internalArraySizeDemo", "sourceCollection", "updateInformation", "userInformation" ]An alternate query can be the following −> show collections;The following is the output −copyThisCollectionToSampleDatabaseDemo deleteDocuments deleteDocumentsDemo deleteInformation employee internalArraySizeDemo sourceCollection updateInformation userInformation