Submission #1127754

#	Time	Username	Problem	Language	Result	Execution time	Memory
1127754		Zbyszek99	Xor Sort (eJOI20_xorsort)	C++20	100 / 100	6 ms	972 KiB

xorsort

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    int n,t;
    cin >> n >> t;
    vi arr(n+1);
    vi arr2(n+1);
    rep(i,n) cin >> arr[i+1];
    rep2(i,1,n) arr2[i] = arr[i];
    vector<pii> ans;
    if(t == 1)
    {
        vector<pii> sort_arr;
        rep(i,n) sort_arr.pb({-arr[i+1],i+1});
        sort(all(sort_arr));
        rep(i,n)
        {
            rep2(j,1,n-1-i)
            {
                ans.pb({j,j+1});
                arr[j] ^= arr[j+1];
            }
            pii m = {-1,-1};
            rep2(j,1,n-i)
            {
                m = max(m,{arr2[j],j});
            }
            int x = m.ss;
          //  cout << x << " x\n";
          //  rep2(k,1,n) cout << arr[k] << " ";
           // cout << " arr\n";
            rep2(j,x,n-1-i)
            {
                ans.pb({j+1,j});
                arr[j+1] ^= arr[j];
            }
            for(int j = x-2; j >= 1; j--)
            {
                ans.pb({j,j+1});
                arr[j] ^= arr[j+1];
            }
            rep2(i,x,n-1)
            {
                arr2[i] = arr2[i+1];
            }
          //  rep2(k,1,n) cout << arr[k] << " ";
          //  cout << " arr\n";
         //   cout << "\n";
        }
        for(int i = n-1; i >= 1; i--)
        {
            ans.pb({i,i+1});
            arr[i] ^= arr[i+1];
        }
       // rep2(k,1,n) cout << arr[k] << " ";
       // cout << " arr\n";
    }
    if(t == 2)
    {
        int cur_suf = n;
        for(int bit = 19; bit >= 0; bit--)
        {
            bool was = false;
            rep2(i,1,cur_suf)
            {
                if(arr[i] & (1 << bit))
                {
                    was = true;
                    int cur = i-1;
                    while(cur >= 1 && (arr[cur] & (1 << bit)) == 0)
                    {
                        ans.pb({cur,cur+1});
                        arr[cur] ^= arr[cur+1];
                        cur--;
                    }
                    cur = i+1;
                    while(cur <= cur_suf && (arr[cur] & (1 << bit)) == 0)
                    {
                        ans.pb({cur,cur-1});
                        arr[cur] ^= arr[cur-1];
                        cur++;
                    }
                }
            }
            if(was == true)
            {
                rep2(i,2,cur_suf)
                {
                    ans.pb({i-1,i});
                    arr[i-1] ^= arr[i];
                }
                cur_suf--;
            }
          //  rep2(i,1,n) cout << arr[i] << " ";
           // cout << " arr\n";
        }
    }
    cout << siz(ans) << "\n";
    forall(it,ans) cout << it.ff << " " << it.ss << "\n";
}

• Subtask 1: 25 / 25
• Subtask 2: 35 / 35
• Subtask 3: 40 / 40