Submission #1150448

#	Time	Username	Problem	Language	Result	Execution time	Memory
1150448		fryingduc	Port Facility (JOI17_port_facility)	C++20	100 / 100	855 ms	67052 KiB

port_facility

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

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

const int maxn = 2e6 + 6;
const int mod = 1e9 + 7;
int n, l[maxn], r[maxn];
int ord[maxn];
int lab[maxn];

int find(int u) {
  return lab[u] < 0 ? u : lab[u] = find(lab[u]);
}

void join(int u, int v) {
  u = find(u), v = find(v);
  if (u == v) return;
  if (lab[u] > lab[v]) swap(u, v);
  lab[u] += lab[v];
  lab[v] = u;
}

void solve() {
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> l[i] >> r[i];
  }
  iota(ord + 1, ord + n + 1, 1);
  sort(ord + 1, ord + n + 1, [](const int &x, const int &y) -> bool {
    return l[x] < l[y];
  });
  for (int i = 1; i <= n + n; ++i) {
    lab[i] = -1;
  }
  set<pair<int, int>> s;
  for (int i = 1; i <= n; ++i) {
    auto ft = s.lower_bound(make_pair(l[ord[i]], -1));
    auto se = s.lower_bound(make_pair(r[ord[i]], -1));
    if (se != s.begin() and se != ft) {
      se--;
      while (ft != s.end()) {
        join(ord[i] + n, ft->second);
        join(ord[i], ft->second + n);
        if (find(ft->second) == find(se->second)) break;
        ++ft;
      }
    }
    s.insert(make_pair(r[ord[i]], ord[i]));
  }
  int ans = 1;
  for (int i = 1; i <= n; ++i) {
    if (find(i) == find(i + n)) {
      cout << 0;
      return;
    }
    if (lab[i] < 0) {
      ans = ans + ans;
      if (ans >= mod) ans -= mod;
    }
  }
  cout << ans;
}

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  solve();

  return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 56 / 56
• Subtask 4: 22 / 22