제출 #45566

#제출 시각아이디문제언어결과실행 시간메모리
45566qoo2p5Port Facility (JOI17_port_facility)C++17
22 / 100
6095 ms384184 KiB
#include <bits/stdc++.h> using namespace std; typedef long long ll; const int INF = (int) 1e9 + 1e6 + 123; const ll LINF = (ll) 1e18 + 1e9 + 123; #define rep(i, s, t) for (auto i = (s); i < (t); ++(i)) #define per(i, s, t) for (auto i = (s); i >= (t); --(i)) #define sz(x) ((int)(x).size()) #define mp make_pair #define pb push_back #define all(x) (x).begin(), (x).end() bool mini(auto &x, const auto &y) { if (y < x) { x = y; return 1; } return 0; } bool maxi(auto &x, const auto &y) { if (y > x) { x = y; return 1; } return 0; } void run(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); run(); return 0; } const int N = (int) 1e6 + 123; const ll MOD = (ll) 1e9 + 7; int n; int a[N], b[N]; vector<int> g[N]; int col[N]; void dfs(int v, int cc = 1) { col[v] = cc; for (int u : g[v]) { if (!col[u]) { dfs(u, 3 - cc); } if (col[u] != 3 - cc) { cout << "0\n"; exit(0); } } } bool closed[N]; pair<int, bool> what[2 * N]; void run() { cin >> n; rep(i, 0, n) { cin >> a[i] >> b[i]; a[i]--; b[i]--; what[a[i]] = {i, 0}; what[b[i]] = {i, 1}; } int e = 0; vector<int> st, tmp; rep(i, 0, 2 * n) { int v = what[i].first; if (what[i].second) { while (1) { int t = st.back(); st.pop_back(); if (t == v) { break; } if (!closed[t]) { tmp.pb(t); } } for (int u : tmp) { g[u].pb(v); g[v].pb(u); e++; } while (sz(tmp)) { int u = tmp.back(); tmp.pop_back(); st.pb(u); } closed[v] = 1; } else { st.pb(v); } } ll ans = 1; rep(i, 0, n) { if (!col[i]) { dfs(i); ans = (ans * 2) % MOD; } } cout << ans << "\n"; }
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