Submission #695053

#	Time	Username	Problem	Language	Result	Execution time	Memory
695053		null_awe	Joker (BOI20_joker)	C++14	0 / 100	0 ms	212 KiB

Joker

#include <iostream>
#include <vector>
#include <set>
#include <queue>
using namespace std;

#define pii pair<int, int>

struct link_cut_tree {

  int n;

  set<pii> edges;

  vector<int> r, p;

  link_cut_tree(int n) : n(n), r(n, 1), p(n) {
    for (int i = 0; i < n; ++i) p[i] = i;
  }

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

  bool same(int a, int b) {
    return find(a) == find(b);
  }

  int sz(int a) {
    return r[find(a)];
  }

  void link(int a, int b) {
    a = find(a), b = find(b);
    if (a == b) return;
    if (r[a] < r[b]) swap(a, b);
    p[b] = a, r[a] += r[b];
  }

  void calc() {
    for (int i = 0; i < n; ++i) r[i] = 1, p[i] = i;
    for (pii edge : edges) link(edge.first, edge.second);
  }

  void add(int a, int b) {
    // cout << "ADD " << a + 1 << ' ' << b + 1 << '\n';
    edges.insert({a, b});
    calc();
  }

  void erase(int a, int b) {
    // cout << "ERASE " << a + 1 << ' ' << b + 1 << '\n';
    edges.erase({a, b});
    calc();
  }
};

vector<bool> color;
vector<set<int>> adj;

vector<int> until;

int main() {
  int n, m, q; cin >> n >> m >> q;
  vector<pii> edges(m);
  for (int i = 0; i < m; ++i) cin >> edges[i].first >> edges[i].second;
  for (int i = 0; i < m; ++i) --edges[i].first, --edges[i].second;
  color.resize(n), adj.resize(n), until.resize(m);
  link_cut_tree lct(n);
  int at = m - 1;
  while (at >= 0) {
    pii p = edges[at];
    int a = p.first, b = p.second;
    if (lct.same(a, b)) {
      if (color[a] == color[b]) break;
      --at;
      adj[a].insert(b);
      adj[b].insert(a);
      lct.add(a, b);
      continue;
    } else {
      int asz = lct.sz(a), bsz = lct.sz(b);
      if (asz < bsz) swap(a, b);
      color[b] = !color[a];
      set<int> vis; vis.insert(b);
      queue<int> q; q.push(b);
      while (q.size()) {
        int v = q.front(); q.pop();
        for (int u : adj[v]) {
          if (vis.count(u)) continue;
          vis.insert(u);
          color[u] = !color[v];
        }
      }
      if (asz < bsz) swap(a, b);
      --at;
      adj[a].insert(b);
      adj[b].insert(a);
      lct.add(a, b);
    }
    // for (int c : color) cout << c << ' ';
    // cout << '\n';
  }
  ++at;
  until[0] = at - 1;
  for (int i = 1; i < m; ++i) {
    while (at <= m) {
      pii p = edges[i - 1];
      int a = p.first, b = p.second;
      // cout << i << ' ' << at << '\n';
      if (lct.same(a, b) && color[a] == color[b] && at < m) {
        p = edges[at];
        a = p.first, b = p.second;
        ++at;
        adj[a].erase(b);
        adj[b].erase(a);
        lct.erase(a, b);
      } else {
        adj[a].insert(b);
        adj[b].insert(a);
        if (!lct.same(a, b)) {
          int asz = lct.sz(a), bsz = lct.sz(b);
          if (asz < bsz) swap(a, b);
          color[b] = !color[a];
          set<int> vis; vis.insert(b);
          queue<int> q; q.push(b);
          while (q.size()) {
            int v = q.front(); q.pop();
            for (int u : adj[v]) {
              if (vis.count(u)) continue;
              vis.insert(u);
              color[u] = !color[v];
            }
          }
          if (asz < bsz) swap(a, b);
        }
        lct.add(a, b);
        break;
      }
    // for (int c : color) cout << c << ' ';
    // cout << '\n';
    }
    until[i] = at - 1;
  }
  // for (int num : until) cout << num + 1 << ' ';
  // cout << '\n';
  for (int i = 0; i < q; ++i) {
    int a, b; cin >> a >> b; --a, --b;
    cout << (until[a] <= b ? "YES\n" : "NO\n");
  }
  return 0;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 8
• Subtask 3: 0 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29