Scanner s = new Scanner(System.in); int t = s.nextInt();

    // Stream to read and process input pairs
    Set<String> uniquePairs = new HashSet<>();

    // We use a Stream to process the input and maintain uniqueness
    IntStream.range(0, t).forEach(i -> {
        String left = s.next();
        String right = s.next();

        // Create the two possible pair strings
        String pair1 = left + " " + right;
        String pair2 = right + " " + left;

        // Add the lexicographically smaller of the two pairs to the set
        uniquePairs.add(Stream.of(pair1, pair2)
                              .min(String::compareTo) // Get the lexicographically smaller string
                              .get());

        // Print the current number of unique pairs
        System.out.println(uniquePairs.size());
    });

If you got a problem with the test case 5 try with lexicographic order:

 Set<String> hs = new HashSet<>();
        for (int i = 0; i < t; i++) {
            String first = pair_left[i];
            String second = pair_right[i];

            if (first.compareTo(second) > 0) {
                String temp = first;
                first = second;
                second = temp;
            }

            hs.add(first + "," + second);
            System.out.println(hs.size());
        }

Test case 5 has failed in my case.

This is my code that I wrote:- import java.io.; import java.util.; import java.text.; import java.math.; import java.util.regex.*;

public class Solution { public static void main(String[] args) { Scanner s = new Scanner(System.in); int t = s.nextInt(); String [] pair_left = new String[t]; String [] pair_right = new String[t];

    for (int i = 0; i < t; i++) {
        pair_left[i]  = s.next();
        pair_right[i] = s.next();
    }
    s.close();

    HashSet<String> set = new HashSet(t);
    for (int i = 0; i < t; i++) {
        set.add(pair_left[i] + " " + pair_right[i]);
        System.out.println(set.size());
    }
}

}

Is there any error in this code as one last test case is failing?

Set<String> mySet = new HashSet<>();
for(int i = 0; i < t; i++) {
	mySet.add(pair_left[i] + " " + pair_right[i]);
	System.out.println(mySet.size());
}

/@Author : Rehan/ Set hashSet = new HashSet<>();

    for(int i = 0; i<t; i++){
        String pair = pair_left[i]+","+pair_right[i];
        hashSet.add(pair);
        System.out.println(hashSet.size());
    }