The part that says (a,b) is not the same as (b,a) is not correct. The solution counts ni kg and kg ni as the same. This fixes Test 5. The test case is not correct, or the task definition.

Please fix Test 5. The Expected results are not correct. It goes wrong at line 191.

    HashSet<String> hashSet = new HashSet<String>();
    for (int i = 0; i < t; i++) {
        String pair;
        if (pair_left[i].compareTo(pair_right[i]) < 0) {
            pair = pair_left[i] + " " + pair_right[i];
        } else {
            pair = pair_right[i] + " " + pair_left[i];
        }

        hashSet.add(pair);
        System.out.println(hashSet.size());
    }

Solved case5: //Write your code here HashSet pairs = new HashSet<>();

for (int i = 0; i < t; i++) {
    // Create unique pair representation
    String pair = pair_left[i] + " " + pair_right[i];
    // Add to HashSet (automatically handles duplicates)

    // Print current size after each addition
    String inverse_pair  =  pair_right[i] + " " + pair_left[i];
        if(!pairs.contains(inverse_pair)) 
        pairs.add(pair);
        System.out.println(pairs.size());
}

any one help ee to solve the error in this code 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();
    }

    // Write your code here
    HashSet<String> pairs = new HashSet<>();

    for (int i = 0; i < t; i++) {
        // Create unique pair representation
        String pair = pair_left[i] + " " + pair_right[i];
        // Add to HashSet (automatically handles duplicates)
        pairs.add(pair);
        // Print current size after each addition
        System.out.println(pairs.size());
    }
}

}