Problem: 2052A - Adrenaline Rush
Language: java

Solution 1 (runtime: 968 ms):
//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
           // System.out.println("starting passing phase, arr2 is " + Arrays.toString(arr2) + " and curNum is " + curNum + " and start: " + startIdx);
            for (int j = startIdx-1; j >= 0; j--) {
                moves.add(arr2[j+1] + " " +  arr2[j]);
                swap(arr2, j);
                //System.out.println("passed 1, move was " + moves.getLast());
            }
            for (int j = 0; j < startIdx; j++) {
                map2.put(arr2[j], j);
            }
            startIdx = map2.get(curNum);
            // 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) {
                //System.out.println("starting going back phase");
                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++;
            //        pw.println("arr2:" + Arrays.toString(arr2) + " and last move was " + moves.getLast());
                }
            }
            for (int j = 0; j < startIdx; j++) {
                map2.put(arr2[j], j);
            }
          //  System.out.println("arr2 at the end of the process:" + Arrays.toString(arr2));
        }
        //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();
    }
}


Solution 2 (runtime: 1093 ms):

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

/**
 * Problem    = cf2052a
 * Date       = Mon Jan 27 23:11:17 PST 2025
 */
public class cf2052a {

  static class Pair {
    int x,y;
    Pair(int x, int y){
      this.x=x;this.y=y;
    }
  }

  public void run() {
    int n = in.nextInt();
    int[] p = new int[n+1];
    for(int i = 1; i <= n; ++i){
      p[i]=in.nextInt();
    }
    Set<Integer> s = new HashSet<>();
    
    var pairs = new LinkedList<Pair>();
    for(int i = 1; i <= n; ++i){
      for(int j = p[i]+1; j <= n; ++j){
        if (!s.contains(j)){
          pairs.add(new Pair(j,p[i]));
        }
      }
      for(int j = n; j > 0; j--){
        if (p[i]==j) continue;
        if (!s.contains(j)){
          pairs.add(new Pair(p[i],j));
        }
      }
      s.add(p[i]);
    }
    out.println(pairs.size());
    for(var pair : pairs)
      out.println(pair.x + " " + pair.y);
  }

  /////////////////////////////////////////////////////////////////////////////////
  static InputStream in(){try{if(file!=null)return new FileInputStream(file+".in");
  return System.in;}catch(Exception e){throw new RuntimeException(e);}}static
  OutputStream out(){try{if(file!=null)return new FileOutputStream(file+".out");
  return System.out;}catch(Exception e){throw new RuntimeException(e);}}IR in=new
  IR(in());PrintWriter out=new PrintWriter(out());void c(){out.close();}static
  class IR{BufferedReader r;StringTokenizer t=null;IR(InputStream s){r=new
  BufferedReader(new InputStreamReader(s),32768);}boolean p(){while(t==null||
  !t.hasMoreTokens()){try{String l=r.readLine();if(l==null)return false;t=new
  StringTokenizer(l);}catch(IOException e){throw new RuntimeException(e);}}return
  true;}boolean hasNext(){return p();}String next(){p();return t.nextToken();}int
  nextInt(){return Integer.parseInt(next());}long nextLong(){return Long.parseLong(
  next());}double nextDouble(){return Double.parseDouble(next());}}public static
  void main(String[]args){cf2052a t=new cf2052a();t.run();t.c();}
  /////////////////////////////////////////////////////////////////////////////////
  static String file;
}