Submission #956790

#	Time	Username	Problem	Language	Result	Execution time	Memory
956790		Sharky	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	100 / 100	1505 ms	87348 KiB

joitter2

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

#define int long long
#define siz(x) (int)x.size()
const int N = 100005;

int p[N], sz[N], ans = 0;
map<pair<int, int>, int> mp;
set<int> st[N], g1[N], g2[N];
queue<pair<int, int>> q;

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

void uni(int u, int v) {
    if (u == v) return;
    mp[{u, v}]++;
    g1[u].insert(v);
    g2[v].insert(u);
    if (g1[v].count(u)) q.push({u, v});
}

void merge(int u, int v) {
    u = find(u), v = find(v);
    if (u == v) return;
    if (siz(g1[u]) + siz(g2[u]) + siz(st[u]) < siz(g1[v]) + siz(g2[v]) + siz(st[v])) swap(u, v);
    ans += sz[u] * siz(st[v]) + sz[v] * siz(st[u]);
    p[v] = u;
    sz[u] += sz[v];
    for (int i : g1[v]) {
        g2[i].erase(v);
        uni(u, i);
    }
    g1[v].clear();
    for (int i : g2[v]) {
        g1[i].erase(v);
        uni(i, u);
    }
    g2[v].clear();
    for (int i : st[v]) {
        if (st[u].count(i)) ans -= sz[u];
        else st[u].insert(i);
    }
    st[v].clear();
}

int32_t main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        p[i] = i, sz[i] = 1;
        st[i].insert(i);
    }
    while (m--) {
        int u, v;
        cin >> u >> v;
        if (st[find(v)].count(u)) { // need to delete?
            cout << ans << '\n';
            continue;
        }
        if (find(u) == find(v)) {
            cout << ans << '\n';
            continue;
        }
        st[find(v)].insert(u);
        u = find(u), v = find(v);
        ans += sz[v];
        uni(u, v);
        while (!q.empty()) {
            auto [x, y] = q.front();
            q.pop();
            merge(x, y);
        }
        cout << ans << '\n';
    }
}

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