Day 28: RegEx, Patterns, and Intro to Databases In Java | 30 Days Of Code | Hackerrank Programming Solutions

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Link for the ProblemDay 28: RegEx, Patterns, and Intro to Databases – Hacker Rank Solution

Day 28: RegEx, Patterns, and Intro to Databases – Hacker Rank Solution


Today, we’re working with regular expressions. Check out the Tutorial tab for learning materials and an instructional video!

Consider a database table, Emails, which has the attributes First Name and Email ID. Given  rows of data simulating the Emails table, print an alphabetically-ordered list of people whose email address ends in .

Input Format

The first line contains an integer, , total number of rows in the table.
Each of the  subsequent lines contains  space-separated strings denoting a person’s first name and email ID, respectively.


  • Each of the first names consists of lower case letters  only.
  • Each of the email IDs consists of lower case letters ,  and  only.
  • The length of the first name is no longer than 20.
  • The length of the email ID is no longer than 50.

Output Format

Print an alphabetically-ordered list of first names for every user with a gmail account. Each name must be printed on a new line.

Sample Input

riya [email protected]
julia [email protected]
julia [email protected]
julia [email protected]
samantha [email protected]
tanya [email protected]

Sample Output

Day 28: RegEx, Patterns, and Intro to Databases – Hacker Rank Solution
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Day28RegExPatternsAndIntroToDatabases {
	public static void main(String[] args) {
		Scanner in = new Scanner(;
		int N = in.nextInt();
		List list = new ArrayList();
		for (int a0 = 0; a0 [email protected]";

			Pattern p = Pattern.compile(regExPattern);
			Matcher m = p.matcher(emailID);
			if (m.find()) {

		for (String string : list) {

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