Submission #1260398

#	Time	Username	Problem	Language	Result	Execution time	Memory
1260398		mingga	Port Facility (JOI17_port_facility)	C++20	78 / 100	172 ms	63048 KiB

port_facility

// Author: caption_mingle
#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 1e6 + 7;
int n, d[N], typ[N];
pair<int, int> a[N];

struct SEGTREE {
	vector<int> st;
	int n;
	SEGTREE() {}
	SEGTREE(int n) : n(n) {
		st.resize(n * 4 + 4, -inf);
	}
	void update(int i, int l, int r, int u, int x) {
		if(l > u or r < u) return;
		if(l == r) {
			st[i] = x;
			return;
		}
		int m = (l + r) >> 1;
		update(i * 2, l, m, u, x);
		update(i * 2 + 1, m + 1, r, u, x);
		st[i] = max(st[i * 2], st[i * 2 + 1]);
	}
	int get(int i, int l, int r, int u, int v) {
		if(l > v or r < u) return -inf;
		if(u <= l and r <= v) return st[i];
		int m = (l + r) >> 1;
		return max(get(i * 2, l, m, u, v), get(i * 2 + 1, m + 1, r, u, v));
	}
	void update(int u, int x) {
		update(1, 1, n, u, x);
	}
	int get(int l, int r) {
		return get(1, 1, n, l, r);
	}
} lef, rig;

void dfs(int u) {
	int c = typ[u];
	// cerr << u << ln;
	while(1) {
		int x = rig.get(a[u].fi + 1, a[u].se - 1);
		if(x < a[u].se) break;
		// cerr << x << ' ' << a[u].se << ln;
		int v = d[x];
		typ[v] = c ^ 1;
		rig.update(a[v].fi, -inf);
		lef.update(a[v].se, -inf);
		dfs(v);
	}
	while(1) {
		int x = -lef.get(a[u].fi + 1, a[u].se - 1);
		if(x > a[u].fi) break;
		// cerr << x << ' ' << a[u].fi << ln;
		int v = d[x];
		typ[v] = c ^ 1;
		rig.update(a[v].fi, -inf);
		lef.update(a[v].se, -inf);
		dfs(v);
	}
}

vector<pair<int, int>> vec[2];

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	cin >> n;
	lef = rig = SEGTREE(n * 2);
	for(int i = 1; i <= n; i++) {
		cin >> a[i].fi >> a[i].se;
		d[a[i].fi] = i;
		d[a[i].se] = i;
		lef.update(a[i].se, -a[i].fi);
		rig.update(a[i].fi, a[i].se);
	}
	memset(typ, -1, sizeof typ);
	int ans = 1;
	for(int i = 1; i <= n; i++) {
		if(typ[i] == -1) {
			typ[i] = 0;
			rig.update(a[i].fi, -inf);
			lef.update(a[i].se, -inf);
			dfs(i);
			ans += ans;
			if(ans >= mod) ans -= mod;
		}
	}
	for(int i = 1; i <= n; i++) {
		vec[typ[i]].pb({a[i].fi, i});
		vec[typ[i]].pb({a[i].se, -i});
	}
	for(int i = 0; i < 2; i++) {
		sort(all(vec[i]));
		vector<int> st;
		for(auto [x, id] : vec[i]) {
			if(id > 0) st.pb(id);
			else {
				if(sz(st) == 0 or st.back() + id != 0) {
					cout << 0;
					return 0;
				}
				st.pop_back();
			}
		}
	}
	cout << ans << ln;
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:82:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
port_facility.cpp:83:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |                 freopen(task ".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 56 / 56
• Subtask 4: 0 / 22