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1 Day 1 Algorithms

[2019.01.22] RegEx, Patterns, and Intro to Databases

by 곰돌찌 2019. 1. 22.

Problem


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

Task 
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.

Constraints // 조건

  • 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

6
riya riya@gmail.com
julia julia@julia.me
julia sjulia@gmail.com
julia julia@gmail.com
samantha samantha@gmail.com
tanya tanya@gmail.com

Sample Output

julia
julia
riya
samantha
tanya


How I solved the problem


# 정규표현식을 사용할 때, 자바는 Pattern과 Matcher 클래스를 사용함.

# Sorting까지 해야하는 문제!

# List에 넣기 위해서 클래스를 추가 해줌!


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import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;
 
public class Solution {
 
    private static final Scanner scanner = new Scanner(System.in);
 
    public static void main(String[] args) {
        int N = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
        
        List<Address> addressList = new ArrayList<Address>();
 
        for (int NItr = 0; NItr < N; NItr++) {
            String[] firstNameEmailID = scanner.nextLine().split(" ");
            String firstName = firstNameEmailID[0];
            String emailID = firstNameEmailID[1];
 
            Address address = new Address(firstName, emailID);
            addressList.add(address);
        }
 
        scanner.close();
 
        getNameList(addressList);
    }
 
    public static void getNameList (List<Address> addressList) {
        int addressListCount = addressList.size();
        List<String> matchedList = new ArrayList<String>();
 
        for (int i = 0; i < addressListCount; i++) {
            Address address = addressList.get(i);
            String firstName = address.firstName;
            String emailID = address.emailID;
            boolean isMatch = false;
 
            //Each of the first names consists of lower case letters  only.
            // The length of the first name is no longer than 20.
            Pattern firstNamePattern = Pattern.compile("[a-z]{1,20}");
            Matcher firstNameMatcher = firstNamePattern.matcher(firstName);
 
            //Each of the email IDs consists of lower case letters[a-z] ,@  and . only.
            //The length of the email ID is no longer than 50.
            Pattern emailIdPattern = Pattern.compile("([a-z]{1,40})@gmail\\.com");
            Matcher emailIdMatcher = emailIdPattern.matcher(emailID);
 
            if (firstNameMatcher.find() && emailIdMatcher.find()) {
                isMatch = true;
            } else {
                isMatch = false;
            }
 
            if (isMatch) {
                matchedList.add(firstName);
            }
        }
 
        //alphabetically sorting
        String[] nameList = new String[matchedList.size()];
        nameList = matchedList.toArray(nameList);
        Arrays.sort(nameList);
 
        for(String name : nameList) {
            System.out.println(name);
        }
    }
}
 
class Address {
    String firstName;
    String emailID;
 
    Address (String firstName, String emailID) {
        this.firstName = firstName;
        this.emailID = emailID;
    }
}
cs


[출처 : https://www.hackerrank.com ]


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