#include <bits/stdc++.h> using namespace std; #def...

It seems like your Java code is performing similar logic to the C++ code but with some differences in how data is handled. Let me go over a few potential issues and suggestions for improvement.

Key Issues:

1. Sorting arrays arr and brr:
   • In the C++ code, st and st2 are sets that maintain the order of insertion and also guarantee uniqueness. In Java, you are using ArrayList<int[]> and sorting them based on the first element (x[0]). However, the logic in C++ doesn't involve sorting st and st2; they are just sets, and the order of traversal depends on the set's internal structure.
   • Potential Issue: By sorting the arrays in Java, you may not be simulating the exact behavior of the C++ code, which relies on the natural ordering of sets (likely in increasing order). Instead, by sorting, you might cause the mismatch between the two versions.
2. Index Handling (x and y):
   • Your variables x and y are intended to track the position in arr and brr, respectively. However, the logic for determining whether to increment x or y based on matching values is flawed in your Java code.
   • Specifically, the condition if(brr.get(y)[1]==arr.get(x)[1] && brr.get(y)[2]==arr.get(x)[2]) y++ might not reflect the exact logic intended by the C++ code.

Suggested Changes:

1. Avoid Sorting:
   • Instead of sorting arr and brr, you should treat them as LinkedHashSet in Java to preserve the order of insertion, just like C++ sets do.
2. Fix the Index Logic:
   • The logic for when to increment x and y should be adjusted to match the behavior from C++. Essentially, you should only increment x or y when you are sure that the right set has been processed.

Improved Java Code:

Here is an updated version of your Java code with the necessary fixes:

java
import java.io.*;
import java.util.*;

public class Mainn {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }

    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int tc = sc.nextInt();
        StringBuilder sb = new StringBuilder();

        // Initialize the sets directly instead of sorting.
        Set<List<Integer>> st = new LinkedHashSet<>();
        Set<List<Integer>> st2 = new LinkedHashSet<>();

        for (int i = 0; i <= 350; i++) {
            for (int j = 0; j <= 350; j++) {
                st.add(Arrays.asList(3 * i + 3 * j + 2, 3 * i + 1, 3 * j + 1));
                st.add(Arrays.asList(3 * i + 3 * j + 3, 3 * i + 1, 3 * j + 2));
                st.add(Arrays.asList(3 * i + 3 * j + 3, 3 * i + 2, 3 * j + 1));
                st.add(Arrays.asList(3 * i + 3 * j + 6, 3 * i + 2, 3 * j + 2));
            }
        }

        for (int i = 0; i <= 350; i++) {
            for (int j = 0; j <= 350; j++) {
                st2.add(Arrays.asList(3 * i + 3 * j + 2, 3 * i + 1, 3 * j + 1));
            }
        }

        label:
        while (tc-- > 0) {
            int n = sc.nextInt();
            int[] a = new int[n];
            for (int i = 0; i < n; i++) a[i] = sc.nextInt();

            // Process each query
            for (int it : a) {
                if (it == 1) {
                    // Take from st
                    List<Integer> curr = st.iterator().next();  // Get the first element
                    st.remove(curr);
                    st2.remove(curr);
                    sb.append(curr.get(1)).append(" ").append(curr.get(2)).append("\n");
                } else {
                    // Take from st2
                    List<Integer> curr = st2.iterator().next();  // Get the first element
                    st.remove(curr);
                    st2.remove(curr);
                    sb.append(curr.get(1)).append(" ").append(curr.get(2)).append("\n");
                }
            }
        }

        System.out.print(sb.toString());
    }
}

Key Changes:

1. Replaced Sorting with LinkedHashSet:

   • I used LinkedHashSet instead of sorting the arrays to maintain insertion order.

2. Simplified Logic for Element Removal:

   • For both st and st2, I directly get the first element using iterator().next(), and then remove it from both sets.

3. Output Handling:

   • I used StringBuilder to append the output for efficiency, and at the end, the result is printed.

Performance Consideration:

The LinkedHashSet is used to maintain the insertion order, and the set operations are generally O(1), so the performance should be in line with the original C++ code.

This approach should now match the behavior of the C++ code more closely and give the correct answer.