DEV Community: Ayush Shalya

Dynamic Programming

Ayush Shalya — Thu, 03 Dec 2020 19:10:48 +0000

Dynamic Programming is nothing but optimized version of recursion. Dynamic programming reduce the time complexity of simple recursion from exponential to polynomial.
The basic idea behind dynamic programming to store the results of subproblems so that, we don't have to re-calculate them again and again.
There are two approaches for solving dynamic programming questions :

Tabulation Method or Bottom Up Approach.
Memoization Method or Top Down Approach.

I am going to cover these two approaches in detail in my post. So, don't forget to check my next post.

 💖💖 Keep reading and keep supporting.💖💖

5.How to match word and non word characters.

Ayush Shalya — Tue, 31 Mar 2020 05:26:33 +0000

The expression \w matches every word character and \W matches all non word characters.
Word characters include alphanumeric characters ([a-z][A-Z][0-9]) and underscore(_).

e.g:- String Pattern : \\w\\w\\w
Test String : Dev.to

Note: Use \\ instead of \ in Java.

Sample code in Java:

import java.io.;
import java.util.Scanner;
import java.util.regex.;
class RegexSearch{
public void tester(String Regex_Pattern){
Scanner sc = new Scanner(System.in);
String Test_String = sc.nextLine();
Pattern p = Pattern.compile(Regex_Pattern);
Matcher m = p.matcher(Test_String);
while(m.find()){
System.out.print(m.group());
}
}
}
public class Main {
public static void main(String[] args){
RegexSearch obj = new RegexSearch();
obj.tester("\\w\\w\\w");
}
}

Input: Devv.to
Output: Dev

You can view the code here also.

   👍 Have a nice day,Coders. 👍

4. How to match whitespace and non whitespace characters.

Ayush Shalya — Mon, 30 Mar 2020 06:57:11 +0000

The \s expression any whitespace characters[space,tab] and \S
expression matches every non whitespace characters.
e.g :- String Pattern :- \\S\\s\\S\\s\\S
Test String :- a b c def

Note:- Use \\ instead of \ in Java.

Sample code in Java:

import java.io.;
import java.util.Scanner;
import java.util.regex.;
class RegexSearch{
public void tester(String Regex_Pattern){
Scanner sc= new Scanner(System.in);
String Test_String = sc.nextLine();
Pattern p = Pattern.compile(Regex_Pattern);
Matcher m = p.matcher(Test_String);
while(m.find()){
System.out.print(m.group());
}
}
}
public class Main{
public static void main(String[]args){
RegexSearch obj = new RegexSearch();
obj.tester("\\S\\s\\S\\s\\S");
}
}

You can view the code here also.

Do read my previous blog on Regex.

1.Introduction about Regex

Ayush Shalya ・ Mar 29 '20 ・ 1 min read

#regex #java

2. The dot(.)

Ayush Shalya ・ Mar 29 '20 ・ 1 min read

#regex #java

3.Matching digits and non digits character.

Ayush Shalya ・ Mar 30 '20 ・ 1 min read

#regex #java

                  👍 Have a nice day, Coders.👍

3.Matching digits and non digits character.

Ayush Shalya — Mon, 30 Mar 2020 05:30:24 +0000

The expression \d matches any digit[0-9] character and expression \D matches every non-digit character.

Note :- For java use \\d or \\D instead of \d or\D.

e.g:- Regex Pattern : \\d\\d\\d\\d
Test String : dev community @12456
Explanation : Here \\d expression which is written four times will match
any four digits character.

Sample code in Java:

import java.io.;
import java.util.Scanner;
import java.util.regex.;
class RegexSearch{
public void tester(String Regex_Pattern){
Scanner sc = new Scanner(System.in);
String Test_String = sc.nextLine();
Pattern p = Pattern.compile(Regex_Pattern);
Matcher m = p.matcher(Test_String);
while(m.find()){
System.out.print(m.group());
}
}
}
public class Main{
public static void main(String[] args){
RegexSearch obj = new RegexSearch();
obj.Pattern("\\d\\d\\d\\d\\D");
}
}

Input:- dev community@12456dev
Output:- 1245d

You can view the code here also

Do read my previous blog on REGEX.

1.Introduction about Regex

Ayush Shalya ・ Mar 29 '20 ・ 1 min read

#regex #java

2. The dot(.)

Ayush Shalya ・ Mar 29 '20 ・ 1 min read

#regex #java

    👍 Have a nice day,Coders.👍

2. The dot(.)

Ayush Shalya — Sun, 29 Mar 2020 20:04:10 +0000

The dot(.) matches anything except a new line.
e.g : Regex Pattern :- .
Test String : Hi everyone.
Sample code in java:
import java.io.;
import java.util.Scanner;
import java.util.regex.;
public class RegexSearch {
public void Pattern (String Regex_Pattern){
Scanner sc = new Scanner(System.in);
String Test_String = sc.nextLine();
Pattern p = Pattern.compile(Regex_Pattern);
Matcher m = p.matcher(Test_String);
while(m.find()){
System.out.print(m.group());
}
}
}
public class Main{
public static void main (String[] args){
RegexSearch obj = new RegexSearch();
obj.Pattern(".");
}
}

you can view the code here also.

Do read my first article about regex.

1.Introduction about Regex

Ayush Shalya ・ Mar 29 '20 ・ 1 min read

#regex #java

1.Introduction about Regex

Ayush Shalya — Sun, 29 Mar 2020 19:23:10 +0000

Regular expression is a sequence of characters used for searching of pattern or matching of pattern.
e.g : Regex Pattern :- Java
Test String :- Java , C and Python all are programming languages.

Sample code in java :

import java.io.;
import java.util.Scanner;
import java.util.regex.;
class RegexSearch {
public void Pattern (String Regex_Pattern){
Scanner sc = new Scanner (System.in);
String Test_String = sc.nextLine();
Pattern p = Pattern.compile(Regex_Pattern);
Matcher m = p.matcher(Test_String);
System.out.println(m.find());
}
}
public class Main{
public static void main(String[] args){
RegexSearch obj = new RegexSearch();
obj.Pattern("Java");
}

Input: Java , C and python all are programming languages.
Output: true

You can view code here also.
Have a nice day , Coders.