Problem: 2052A - Adrenaline Rush
Language: Java 21

Previous submission (verdict: Wrong answer on test 4):
//package Practice;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class AdrenalineRush {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        int n = Integer.parseInt(br.readLine());
        int[] arr = new int[n];
        StringTokenizer st = new StringTokenizer(br.readLine());
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < n; i++) {
            arr[i] = Integer.parseInt(st.nextToken());
            map.put(arr[i], i);
         }
        if (n == 1) {
            pw.println("0");
            pw.close();
            return;
        }
        HashMap<Integer, Integer> map2 = new HashMap<>();
        int[] arr2 = new int[n];
        for (int i = 0; i < n; i++) {
            arr2[i] = i+1;
            map2.put(i+1, i);
        }
        ArrayList<String> moves= new ArrayList<>();
        for (int i = n-1; i >= 0; i--) {
            int curNum = arr[i];
            int startIdx = map2.get(curNum);
            int endIdx = map.get(curNum);
            //System.out.println("at i="+i+", curNum is " + curNum + " and start:" + startIdx + " and end:" + endIdx);
            if (startIdx < endIdx) {
                while (startIdx < endIdx) {
                    moves.add(arr2[startIdx+1] + " " + arr2[startIdx]);
                    int temp = arr2[startIdx];
                    map2.put(arr2[startIdx], map2.get(arr2[startIdx]) + 1);
                    map2.put(arr2[startIdx+1], map2.get(arr2[startIdx+1]) - 1);
                    arr2[startIdx] = arr2[startIdx+1];
                    arr2[startIdx+1] = temp;
                    startIdx++;
                }
            }
        }
        //System.out.println("arr2:" + Arrays.toString(arr2));
        HashSet<String> moveSet = new HashSet<>();
        moveSet.addAll(moves);
        for (int i = 0; i < n - 1; i++) {
            if (!moveSet.contains(arr2[i] + " " + arr2[i+1]) && !moveSet.contains(arr2[i+1] + " " + arr2[i])) {
                moves.add(arr2[i+1] + " " + arr2[i]);
                moves.add(arr2[i] + " " + arr2[i+1]);
            }
        }
        pw.println(moves.size());
        for (String move: moves) {
            pw.println(move);
        }
        // do extra stuff

        pw.close();
        br.close();
    }
}


Submission (verdict: Wrong answer on test 6):
//package Practice;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class AdrenalineRush {
    public static void swap(int[] arr, int l) {
        int temp = arr[l];
        arr[l] = arr[l+1];
        arr[l+1] = temp;
    }
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        int n = Integer.parseInt(br.readLine());
        int[] arr = new int[n];
        StringTokenizer st = new StringTokenizer(br.readLine());
        HashMap<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < n; i++) {
            arr[i] = Integer.parseInt(st.nextToken());
            map.put(arr[i], i);
         }
        if (n == 1) {
            pw.println("0");
            pw.close();
            return;
        }
        HashMap<Integer, Integer> map2 = new HashMap<>();
        int[] arr2 = new int[n];
        for (int i = 0; i < n; i++) {
            arr2[i] = i+1;
            map2.put(i+1, i);
        }
        ArrayList<String> moves= new ArrayList<>();
        for (int i = n-1; i >= 0; i--) {
            int curNum = arr[i];
            int startIdx = map2.get(curNum);
            int endIdx = map.get(curNum);
            // pass everything that starts in front
            for (int j = startIdx-1; j >= 0; j--) {
                moves.add(arr2[j+1] + " " +  arr2[j]);
                swap(arr2, j);
            }
            for (int j = 0; j < startIdx; j++) {
                map2.put(arr2[j], j);
            }
            startIdx = 0;
            // then get passed by everything that ends in front
            //System.out.println("at i="+i+", curNum is " + curNum + " and start:" + startIdx + " and end:" + endIdx);
            if (startIdx < endIdx) {
                while (startIdx < endIdx) {
                    //System.out.println("one move with num = " + curNum);
                    moves.add(arr2[startIdx+1] + " " + arr2[startIdx]);
                    int temp = arr2[startIdx];
                    map2.put(arr2[startIdx], map2.get(arr2[startIdx]) + 1);
                    map2.put(arr2[startIdx+1], map2.get(arr2[startIdx+1]) - 1);
                    arr2[startIdx] = arr2[startIdx+1];
                    arr2[startIdx+1] = temp;
                    startIdx++;
                }
            }
        }
        //System.out.println("arr2:" + Arrays.toString(arr2));
        /*HashSet<String> moveSet = new HashSet<>();
        moveSet.addAll(moves);
        for (int i = 0; i < n - 1; i++) {
            if (!moveSet.contains(arr2[i] + " " + arr2[i+1]) && !moveSet.contains(arr2[i+1] + " " + arr2[i])) {
                moves.add(arr2[i+1] + " " + arr2[i]);
                moves.add(arr2[i] + " " + arr2[i+1]);
            }
        }*/
        pw.println(moves.size());
        for (String move: moves) {
            pw.println(move);
        }
        // do extra stuff

        pw.close();
        br.close();
    }
}