제출 #978852

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
978852		Mr_Husanboy	조이터에서 친구를 만드는건 재밌어 (JOI20_joitter2)	C++17	100 / 100	1268 ms	67744 KiB

joitter2

//#pragma GCC optimize("Ofast,O3")
//#pragma GCC target("avx,avx2")
#include <bits/stdc++.h>
using namespace std;



#ifdef LOCAL
#include "debugger.cpp"
#else
#define debug(...)
#endif
template<class T>
int len(T &a){
    return a.size();
}

using ll = long long;
using pii = pair<int,int>;
#define all(a) (a).begin(), (a).end()
#define ff first
#define ss second
string fileio = "";

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const int MOD = 1e9 + 7;
const int inf = 1e9;
const ll infl = 1e18;
const int maxn = 1e5 + 1;

struct DSU{
    vector<int> par, sz; int n;
    DSU (int _n){
        n = _n;
        par.resize(n);
        iota(all(par), 0);
        sz.assign(n, 1);
    }
    DSU (){}
    int get(int a){
        return (par[a] == a ? a : par[a] = get(par[a]));
    }

    void init(int _n){
        n = _n;
        par.resize(n);
        iota(all(par), 0);
        sz.assign(n, 1);
    }

    void unite(int a, int b){
        a = get(a);
        b = get(b);
        if(a == b) return;
        if(sz[a] < sz[b]) swap(a,b);
        sz[a] += sz[b];
        par[b] = a;
    }

    void link(int a, int b){
        a = get(a); b = get(b);
        if(a == b) return;
        sz[b] += sz[a];
        par[a] = b;
    }
};


void solve(){
    int n, m; cin >> n >> m;
    vector<set<int>> half(n), rhalf(n);
    vector<set<int>> lead(n);
    for(int i = 0; i < n; i ++) lead[i].insert(i);
    DSU t(n);
    ll ans = 0;

    queue<pair<int,int>> q;

    auto half_edge = [&](int a, int b){
        //debug(a + 1, b + 1);
        half[a].insert(b);
        rhalf[b].insert(a);
        if(half[b].count(a)){
            q.push({a, b});
        }
    };

    while(m --){
        int a, b; cin >> a >> b; a --; b --;

        int la = t.get(a), lb = t.get(b);
        if(la == lb || lead[lb].count(a)){
            cout << ans << '\n';
            continue;
        }   

        lead[lb].insert(a);
        half_edge(la, lb);

        ans += t.sz[lb];

        while(!q.empty()){
            tie(a, b) = q.front(); q.pop();
            a = t.get(a), b = t.get(b);
            if(a == b) continue;

            ans += 1ll * t.sz[a] * len(lead[b]) + 1ll * t.sz[b] * len(lead[a]);

            if(len(lead[a]) > len(lead[b])) swap(a, b);
            t.link(a, b);


            for(auto u : lead[a]){
                if(lead[b].count(u)) ans -= t.sz[b];
                else lead[b].insert(u);
            }
            lead[a].clear();

            half[a].erase(b); half[b].erase(a);
            rhalf[b].erase(a); rhalf[a].erase(b);

            for(auto i : half[a]){
                rhalf[i].erase(b);
                half_edge(b, i);
            }

            for(auto i : rhalf[a]){
                half[i].erase(a);
                half_edge(i, b);
            }
        }
        cout << ans << '\n';
    }
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    auto start = chrono::high_resolution_clock::now();
    #ifndef LOCAL
    if(fileio.size()){
        freopen((fileio + ".in").c_str(), "r", stdin);
        freopen((fileio + ".out").c_str(), "w", stdout);
    }
    #endif
    int testcases = 1;
    #ifdef Tests
    cin >> testcases;
    #endif
    while(testcases --){
        solve();
        if(testcases) cout << '\n';
        #ifdef LOCAL
        else cout << '\n';
        cout << "_________________________" << endl;
        #endif
    }
    #ifdef LOCAL
    auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
    
    cout << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
    #endif
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

joitter2.cpp: In function 'int main()':
joitter2.cpp:138:10: warning: variable 'start' set but not used [-Wunused-but-set-variable]
  138 |     auto start = chrono::high_resolution_clock::now();
      |          ^~~~~
joitter2.cpp:141:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  141 |         freopen((fileio + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
joitter2.cpp:142:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  142 |         freopen((fileio + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 1 / 1
• Subtask 2: 16 / 16
• Subtask 3: 83 / 83