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Tag Content Extractor

Tag Content Extractor

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In a tag-based language like XML or HTML, contents are enclosed between a start tag and an end tag like <tag>contents</tag>. Note that the corresponding end tag starts with a /.

Given a string of text in a tag-based language, parse this text and retrieve the contents enclosed within sequences of well-organized tags meeting the following criterion:

  1. The name of the start and end tags must be same. The HTML code <h1>Hello World</h2> is not valid, because the text starts with an h1 tag and ends with a non-matching h2 tag.
  2. Tags can be nested, but content between nested tags is considered not valid. For example, in <h1><a>contents</a>invalid</h1>, contents is valid but invalid is not valid.
  3. Tags can consist of any printable characters.

Input Format

The first line of input contains a single integer, N (the number of lines).
The N subsequent lines each contain a line of text.

Constraints

  • 1 < N < 100
  • Each line contains a maximum of 104 printable characters.
  • The total number of characters in all test cases will not exceed 106.

Output Format

For each line, print the content enclosed within valid tags.
If a line contains multiple instances of valid content, print out each instance of valid content on a new line; if no valid content is found, print None.

Sample Input

4
<h1>Nayeem loves counseling</h1>
<h1><h1>Sanjay has no watch</h1></h1><par>So wait for a while</par>
<Amee>safat codes like a ninja</amee>
<SA premium>Imtiaz has a secret crush</SA premium>

Sample Output

Nayeem loves counseling
Sanjay has no watch
So wait for a while
None
Imtiaz has a secret crush

Solution:

import java.util.*;
import java.util.regex.*;

public class Solution {
    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int testCases = Integer.parseInt(in.nextLine());
        final Pattern pattern = Pattern.compile("<(.+)>([^<>]+)</\\1>");
        while (testCases > 0) {
            String line = in.nextLine();

            Matcher matcher = pattern.matcher(line);

            if (!matcher.find()) {
                System.out.println("None");
            } else {
                System.out.println(matcher.group(2));
                while (matcher.find()) {
                    System.out.println(matcher.group(2));
                }
            }

            testCases--;
        }
    }

}