Submission #981972

#	Time	Username	Problem	Language	Result	Execution time	Memory
981972		kh0i	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	100 / 100	902 ms	69116 KiB

joitter2

#include "bits/stdc++.h"
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif

using ll = long long;
using pii = pair<int, int>;

#define F first
#define S second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
    assert(l <= r);
    return uniform_int_distribution<ll> (l, r)(rng);
}

const int N = 1e5 + 3;

int n, m;

int p[N];
ll sz[N];
set<int> fl[N], rfl[N], comp[N];
queue<pii> to_merge;
ll ans;

int find(int x) { return x == p[x] ? x : p[x] = find(p[x]); }

void insert_weak(int u, int v){
    fl[u].insert(v);
    rfl[v].insert(u);
    if(fl[v].count(u))
        to_merge.push({u, v});
}

int dsu_sz(int u) { return sz(comp[u]) + sz(fl[u]) + sz(rfl[u]); }

void merge_set(int u, int v){
    u = find(u), v = find(v);
    if(u == v) return;
    if(dsu_sz(u) < dsu_sz(v)) swap(u, v);

    ans += (sz[v] * sz(comp[u])) + (sz[u] * sz(comp[v]));
    p[v] = u;
    sz[u] += sz[v];

    for(int i : comp[v]){
        if(comp[u].count(i)) ans -= sz[u];
        else comp[u].insert(i);
    }

    fl[u].erase(v); rfl[v].erase(u);
    fl[v].erase(u); rfl[u].erase(v);

    for(int i : fl[v]){
        rfl[i].erase(v);
        insert_weak(u, i);
    }

    for(int i : rfl[v]){
        fl[i].erase(v);
        insert_weak(i, u);
    }
}

void solve(){
    cin >> n >> m;
    for(int i = 1; i <= n; ++i){
        sz[i] = 1, p[i] = i;
        comp[i].insert(i);
    }
    while(m--){
        int u, v;
        cin >> u >> v;

        v = find(v);

        if(find(u) != v and !comp[v].count(u)){
            comp[v].insert(u);
            ans += sz[v];

            u = find(u);
            insert_weak(u, v);

            while(!to_merge.empty()){
                merge_set(to_merge.front().F, to_merge.front().S);
                to_merge.pop();
            }
        }

        cout << ans << '\n';
    }
}

int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(0);
    #define task "troll"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int test = 1;
//    cin >> test;
    for(int i = 1; i <= test; ++i){
//        cout << "Case #" << i << ": ";
        solve();
    }
    #ifdef LOCAL
        cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
    #endif
    return 0;
}

Compilation message (stderr)

joitter2.cpp: In function 'int32_t main()':
joitter2.cpp:106:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  106 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
joitter2.cpp:107:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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