Submission #518677

#	Time	Username	Problem	Language	Result	Execution time	Memory
518677		akhan42	Port Facility (JOI17_port_facility)	C++17	78 / 100	3858 ms	1048580 KiB

port_facility

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

#define F first
#define S second
#define forn(i, n) for(int i = 0; i < n; ++i)
#define forbn(i, b, n) for(int i = b; i < n; ++i)
#define sz(v) (int)v.size()
#define pb push_back
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define mp make_pair
#define at(m, p) (m.find(p) != m.end() ? m[p] : 0)

typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long long ll;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

template <class T> inline void mineq(T &a, T b) { a = min(a, b); }
template <class T> inline void maxeq(T &a, T b) { a = max(a, b); }


const long long mod = 1000 * 1000 * 1000 + 7;

inline long long mpow(long long b, long long ex) {
    long long r = 1;

    while(ex) {
        if(ex & 1)
        	r = (r * b) % mod;
        ex = ex >> 1;
        b = (b * b) % mod;
    }
    return r;
}


struct Seg {
	int n;
	vector<set<int>> sl;

	void init(int n, vi &vals) {
		this->n = n;
		sl.resize(2 * n);

		forn(i, n) {
			sl[i + n].insert(vals[i]);
		}
		for(int i = n - 1; i > 0; i--) {
			sl[i].insert(all(sl[2 * i]));
			sl[i].insert(all(sl[2 * i + 1]));
		}
	}

	void add(vi &nb, int v, int val, bool is_left) {
		auto it = sl[v].lower_bound(val);
		if(is_left) {
			copy(it, sl[v].end(), back_inserter(nb));
		} else {
			copy(sl[v].begin(), it, back_inserter(nb));
		}
	}

	void query(vi &nb, int l, int r, int bd, bool is_left) {
		for(l += n, r += n + 1; l < r; l >>= 1, r >>= 1) {
			if(l & 1)
				add(nb, l++, bd, is_left);
			if(r & 1)
				add(nb, --r, bd, is_left);
		}
	}

	void del(int p, int val) {
		for(p += n; p > 0; p >>= 1)
			sl[p].erase(val);
	}
};


vector<int> att;
int ncomps = 0;
vi l2r, e2i;
vii vlr;
Seg seg;


int ch(int c) {
	return c == 1 ? 2 : 1;
}


void my_push(queue<ii> &q, int node, int color) {
	int l = vlr[node].F, r = vlr[node].S;
	seg.del(l, r);
	seg.del(r, l);

	q.push({node, color});
	att[node] = color;
}


void bfs(int root) {
	ncomps += 1;

	queue<ii> q;
	my_push(q, root, 1);

	while(!q.empty()) {
		int node = q.front().F, color = q.front().S;
		int L = vlr[node].F, R = vlr[node].S;
		q.pop();

		vi nbs;
		seg.query(nbs, L + 1, R - 1, R, true);
		seg.query(nbs, L + 1, R - 1, L, false);

		for(int nb: nbs) {
			my_push(q, e2i[nb], ch(color));
		}
	}
}


void solve() {
	int n;
	cin >> n;
	l2r.resize(2 * n);
	e2i.resize(2 * n);
	att.assign(n, 0);

	forn(i, n) {
		int l, r;
		cin >> l >> r;
		l--; r--;

		l2r[l] = r;
		l2r[r] = l;
		e2i[l] = e2i[r] = i;

		vlr.eb(l, r);
	}

	seg.init(2 * n, l2r);

	forn(i, n) {
		if(!att[i]) {
			bfs(i);
		}
	}

	stack<int> st[2];
	bool bad = false;

	forn(e, 2 * n) {
		int i = e2i[e], c = att[i] - 1;
		if(vlr[i].F == e) {
			st[c].push(i);
		} else {
			if(st[c].top() != i) {
				bad = true;
				break;
			} else {
				st[c].pop();
			}
		}
	}

	cout << (bad ? 0 : mpow(2, ncomps)) << '\n';
}


int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);

//	freopen("gathering.in", "r", stdin);
//	freopen("gathering.out", "w", stdout);

	int t = 1;
//	cin >> t;
	while(t--) {
		solve();
	}
}

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