Your expected output contains domain names not present in the input HTML code

This is way too difficult without any spec on what constitutes a domain. It seems the expected output uses hidden rules for figuring out if a domain is "legal" or not.

This question needs a bit more polish. The instructions and test cases could use more clarity.

1. "www." and "ww2." are expected to be filtered out but this instruction is easy to miss.
2. In the real world, you cannot assume that "www.example.org" and "example.org" resolve to the same place
3. The test case inputs are truncated so it's harder to debug
4. There is no hint for which special characters are valid in a domain name

'graph.facebook.com', 'plus.google.com', 's3.amazonaws.com', 'ssl.gstatic.com' are not there in test case 2 but they show up in expected output

Sigh. I spent far too long before realzing that the regex includes "http" or "https" in their regex.

In normal html this is a valid link

<a href="//google.com">Google.com</a>

I was pulling those domains with my regex, but the solution does not.

Python one line:

import re

print ';'.join(sorted(set([i.group(2) for i in re.finditer(r'https?://(www2?\.)?(([A-Za-z0-9-]+\.)+[A-Za-z0-9]+)', '\n'.join(raw_input() for _ in range(int(raw_input()))))])))

Java 8 Solution

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = Integer.parseInt(in.nextLine().trim());

        Pattern pa = Pattern.compile("http[s]?:\\/\\/(ww[w2]\\.)?(([a-zA-Z0-9\\-]+\\.)+([a-zA-Z\\-])+)");

        TreeSet<String> set = new TreeSet<>();

        while (n-- > 0) {
            String input = in.nextLine();
            Matcher ma = pa.matcher(input);
            while (ma.find()) set.add(ma.group(2));
        }

        for (String str : set) {
            System.out.print((str != set.last()) ? str + ";" : str);
        }
    }
}

Guys I had the same problem as mentioned by others, getting a compile time error on Test Cases #3 and #4 using Python 3. Indeed changing to Python 2 solved the problem, but does anyone know a way to solve this UnicodeDecodeError so that I can also have the solution using Python 3? Thanks in advance!

JS Solution :

function processData(input) {
    var data = input.split('\n');
    var n = parseInt(data[0]);
    var text = data.slice(1).join(' ');
    
    console.log(detectDomains(input).sort().join(';'));
}

var detectDomains = function(input) {
    var domainRE = /https?:\/\/(ww[w2].)?([-\w.]+\.[a-z]+)/ig;
    var domains = new Set();
    input.replace(domainRE, function(_,__,domain) {
        domains.add(domain)
    })
    return Array.from(domains);
}

I am failing on test-case #2 only. I have bought the input and the output. It looks like natural order is not the same ion c# as in the language it was used to produce the expected result. I can not change the ordering in .net just for one single case! Everything else is green.

My output is: coursera.org;coursera-placement-resumes.s3.amazonaws.com;d2wvvaown1ul17.cloudfront.net;eventing.coursera.org;linkedin.com;ogp.me;s3.amazonaws.com;schema.org;ssl.google-analytics.com;thelearningpoint.net

The expected one is: coursera-placement-resumes.s3.amazonaws.com;coursera.org;d2wvvaown1ul17.cloudfront.net;eventing.coursera.org;linkedin.com;ogp.me;s3.amazonaws.com;schema.org;ssl.google-analytics.com;thelearningpoint.net