Submission #1310595

#	Time	Username	Problem	Language	Result	Execution time	Memory
1310595		Tymond	Parking (CEOI22_parking)	C++20	20 / 100	63 ms	141036 KiB

Main

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

struct pair_hash{
  size_t operator()(const pair<int,int>&x)const{
    return hash<long long>()(((long long)x.first)^(((long long)x.second)<<32));
  }
};

const int MAXN = 2e5 + 7;
vi pos[MAXN];
vi vec[MAXN];
vi f = {};
vector<pii> ans = {};
bool ok = true;
int n, m;

void Move(int p, int q){
    if(p == q){
        return;
    }

    ans.pb(mp(p, q));
    int x = vec[p].back();
    if(pos[x][0] == p){
        swap(pos[x][0], pos[x][1]);
    }
    pos[x][1] = q;
    vec[p].pop_back();
    vec[q].pb(x);

    if(sz(f) && q == f.back()){
        f.pop_back();
    }

    if(sz(vec[p]) == 0){
        f.pb(p);
    }
}

int eliminate(int v){
    if(sz(vec[v]) == 0 || sz(vec[v]) == 2){
        return 0;
    }

    int x = vec[v].back();
    int nxt = pos[x][0] + pos[x][1] - v;
    //cerr << v << ' ' << nxt << ' ' << x << '\n';
    if(vec[nxt].back() == vec[v].back()){
        Move(nxt, v);
        if(sz(vec[nxt]) == 1){
            return eliminate(nxt);
        }
        return 0;
    }else{
        return v;
    }
}

void eliminate2(int v){
    if(sz(vec[v]) == 0 || sz(vec[v]) == 2){
        return;
    }

    int x = vec[v].back();
    int nxt = pos[x][0] + pos[x][1] - v;
   // cerr << v << ' ' << nxt << ' ' << x << '\n';
  //  debug(ans);
    if(vec[nxt].back() == vec[v].back()){
        Move(nxt, v);
        if(sz(vec[nxt]) == 1){
            eliminate2(nxt);
        }
    }else{
        int our = v;
        while(67){

           // cerr << our << ' ' << nxt << ' ' << x << '\n';
            if(vec[nxt].back() == vec[our].back()){
                if(sz(f) == 0){
                    cout << "-1\n";
                    exit(0);
                }

                int xd = f.back();
                Move(our, xd);
                Move(nxt, xd);

                if(sz(vec[nxt])){
                    eliminate2(nxt);
                }

                if(sz(vec[our])){
                    eliminate2(our);
                }
                return;
            }else{
                x = vec[nxt].back();
                our = nxt;
                nxt = pos[x][0] + pos[x][1] - our;
            }
        }
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);

    cin >> n >> m;
    for(int i = 1; i <= m; i++){
        int a, b;
        cin >> a >> b;
        if(a != 0){
            pos[a].pb(i);
            vec[i].pb(a);
        }else{
            f.pb(i);
        }

        if(b != 0){
            pos[b].pb(i);
            vec[i].pb(b);
        }
    }

   // debug(ans);
   // debug(f);
    for(int i = 1; i <= m; i++){
        if(sz(vec[i]) == 1){
            eliminate(i);
        }
    }
   // cerr << "XD\n";
    for(int i = 1; i <= m; i++){
        if(sz(vec[i]) == 1){
            eliminate2(i);
        }
    }
  //  debug(ans);
  //  debug(f);
    for(int i = 1; i <= n; i++){
        if(pos[i][0] != pos[i][1] && vec[pos[i][0]].back() == i && vec[pos[i][1]].back() == i){
            //jesteś w wierzchołku do którego wchodzi dwóch
           // cerr << i << '\n';
           // debug(f);
            if(sz(f) == 0){
                cout << "-1\n";
                return 0;
            }

            int xd1 = pos[i][0];
            int xd2 = pos[i][1];
            Move(xd1, f.back());
            Move(xd2, f.back());

            xd1 = eliminate(xd1);
            xd2 = eliminate(xd2);
            //debug(ans);
            if(xd1 && sz(vec[xd1])){
                eliminate2(xd1);
            }
            
            if(xd2 && sz(vec[xd2])){
                eliminate2(xd2);
            }
        }
    }
  //  cerr << "XD2\n";

    //cykle
    for(int i = 1; i <= n; i++){
        if(pos[i][0] == pos[i][1]){
            continue;
        }

        if(sz(f) == 0){
            cout << "-1\n";
            return 0;
        }
        
        int xd = f.back();
        int our = pos[i][0];
        if(vec[our].back() != i){
            our = pos[i][1];
        }

        Move(our, xd);
        eliminate(xd);
        eliminate(our);
    }

    cout << sz(ans) << '\n';
    for(auto ele : ans){
        cout << ele.fi << ' ' << ele.se << '\n';
    }

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 15
• Subtask 5: 0 / 25
• Subtask 6: 0 / 15