Problem: 2052A - Adrenaline Rush
Language: java

Solution 1 (runtime: 1953 ms):
import java.util.*;
import java.io.*;

public class A_Adrenaline_Rush {

    int mod = (int) 1e9 + 7;
    
    public static void main(String[] args) {
        int n = sc.nextInt();
        int[] f = new int[n];
        input(f);
        int[] a = new int[n];
        for(int i=0;i<n;i++) a[i] = i+1;
        List<int[]> l = new ArrayList<>();
        for(int i=1;i<n;i++){
            int j = i;
            while(j>0){
                int temp = a[j];
                a[j] = a[j-1];
                a[j-1] = temp;
                l.add(new int[]{a[j-1],a[j]});
                j--;
            }
        }
        for(int i=0;i<n;i++){
            int pl = f[i];
            // System.out.println(pl);
            int idx = -1;
            for(int j=0;j<n;j++){
                if(a[j]==pl){
                    idx = j;
                    break;
                }
            }
            // System.out.println(idx);
            if(i<idx)    {int j = idx;
                while(j>i){
                    int temp = a[j];
                    a[j] = a[j-1];
                    a[j-1] = temp;
                    l.add(new int[]{a[j-1],a[j]});
                    j--;
                }
                // if(dest>0){
                //     while(j<dest){
                //         int temp = a[j];
                //         a[j] = a[j+1];
                //         a[j+1] = temp;
                //         l.add(new int[]{a[j],a[j+1]});
                //         j++;
                //     }
                // }
            }
            // printArr(a);
        }
        System.out.println(l.size());
        for(int i=0;i<l.size();i++){
            System.out.println(l.get(i)[0] + " " + l.get(i)[1]);
        }
        // printArr(a);
    }
    
    public static void input(Object array) {
        if (array instanceof int[])
            for (int i = 0; i < ((int[]) array).length; i++)
                ((int[]) array)[i] = sc.nextInt();
        else if (array instanceof long[])
            for (int i = 0; i < ((long[]) array).length; i++)
                ((long[]) array)[i] = sc.nextLong();
    }
    
    public static void printArr(Object array) {
        if (array instanceof int[])
            for (int x : (int[]) array)
                System.out.print(x + " ");
        else if (array instanceof long[])
            for (long x : (long[]) array)
                System.out.print(x + " ");
        System.out.println();
    }
    
    public static <T extends Number> long gcd(T a, T b) {
        return b.longValue() == 0 ? a.longValue() : gcd(b, a.longValue() % b.longValue());
    }
    
    static FastReader sc = new FastReader();
    
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;
    
        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }
    
        String next() {
            while (st == null || !st.hasMoreTokens()) {
                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());
        }
    
        double nextDouble() {
            return Double.parseDouble(next());
        }
    
        String nextLine() {
            String str = "";
            try {
                str = br.readLine().trim();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}

Solution 2 (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();
    }
}