Submission #682001

#	Time	Username	Problem	Language	Result	Execution time	Memory
682001		SanguineChameleon	Event Hopping (BOI22_events)	C++17	100 / 100	157 ms	46732 KiB

events

// BEGIN BOILERPLATE CODE

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

#ifdef KAMIRULEZ
	const bool kami_loc = true;
	const long long kami_seed = 69420;
#else
	const bool kami_loc = false;
	const long long kami_seed = chrono::steady_clock::now().time_since_epoch().count();
#endif

const string kami_fi = "kamirulez.inp";
const string kami_fo = "kamirulez.out";
mt19937_64 kami_gen(kami_seed);

long long rand_range(long long rmin, long long rmax) {
	uniform_int_distribution<long long> rdist(rmin, rmax);
	return rdist(kami_gen);
}

long double rand_real(long double rmin, long double rmax) {
	uniform_real_distribution<long double> rdist(rmin, rmax);
	return rdist(kami_gen);
}

void file_io(string fi, string fo) {
	if (fi != "" && (!kami_loc || fi == kami_fi)) {
		freopen(fi.c_str(), "r", stdin);
	}
	if (fo != "" && (!kami_loc || fo == kami_fo)) {
		freopen(fo.c_str(), "w", stdout);
	}
}

void set_up() {
	if (kami_loc) {
		file_io(kami_fi, kami_fo);
	}
	ios_base::sync_with_stdio(0);
	cin.tie(0);
}

void just_do_it();

void just_exec_it() {
	if (kami_loc) {
		auto pstart = chrono::steady_clock::now();
		just_do_it();
		auto pend = chrono::steady_clock::now();
		long long ptime = chrono::duration_cast<chrono::milliseconds>(pend - pstart).count();
		string bar(50, '=');
		cout << '\n' << bar << '\n';
		cout << "Time: " << ptime << " ms" << '\n';
	}
	else {
		just_do_it();
	}
}

int main() {
	set_up();
	just_exec_it();
	return 0;
}

// END BOILERPLATE CODE

// BEGIN MAIN CODE

const int ms = 1e5 + 20;
const int inf = 1e9 + 20;
const int st = 20;
int lg[ms * 2];
int lt[ms];
int rt[ms];
pair<int, int> p[ms * 2];
pair<int, int> mi[ms * 2][st];
int nxt[ms][st];

int get(int lt, int rt) {
	int k = lg[rt - lt + 1];
	return min(mi[lt][k], mi[rt - (1 << k) + 1][k]).second;
}

void query() {
	int u, v;
	cin >> u >> v;
	if (u == v) {
		cout << 0 << '\n';
		return;
	}
	if (lt[v] <= rt[u] && rt[u] <= rt[v]) {
		cout << 1 << '\n';
		return;
	}
	if (rt[u] > rt[v]) {
		cout << "impossible" << '\n';
		return;
	}
	int res = 0;
	for (int k = st - 1; k >= 0; k--) {
		if (lt[nxt[v][k]] > rt[u]) {
			v = nxt[v][k];
			res += (1 << k);
		}
	}
	res += 2;
	v = nxt[v][0];
	if (lt[v] <= rt[u] && rt[u] <= rt[v]) {
		cout << res << '\n';
	}
	else {
		cout << "impossible" << '\n';
	}
}

void just_do_it() {
	for (int i = 2; i < ms * 2; i++) {
		lg[i] = lg[i / 2] + 1;
	}
	int n, q;
	cin >> n >> q;
	for (int i = 1; i <= n; i++) {
		cin >> lt[i] >> rt[i];
	}
	for (int i = 1; i <= n; i++) {
		p[i * 2 - 1] = {lt[i], i};
		p[i * 2] = {rt[i], -i};
	}
	sort(p + 1, p + n * 2 + 1);
	int cnt = 0;
	for (int i = 1; i <= n * 2; i++) {
		if (p[i].first != p[i - 1].first) {
			cnt++;
		}
		if (p[i].second > 0) {
			lt[p[i].second] = cnt;
		}
		else {
			rt[-p[i].second] = cnt;
		}
	}
	for (int i = 1; i <= cnt; i++) {
		mi[i][0] = {inf, -1};
	}
	for (int i = 1; i <= n; i++) {
		mi[rt[i]][0] = min(mi[rt[i]][0], {lt[i], i});
	}
	for (int k = 1; k < st; k++) {
		for (int i = 1; i + (1 << k) - 1 <= cnt; i++) {
			mi[i][k] = min(mi[i][k - 1], mi[i + (1 << (k - 1))][k - 1]);
		}
	}
	for (int i = 1; i <= n; i++) {
		nxt[i][0] = get(lt[i], rt[i]);
	}
	for (int k = 1; k < st; k++) {
		for (int i = 1; i <= n; i++) {
			nxt[i][k] = nxt[nxt[i][k - 1]][k - 1];
		}
	}
	for (int i = 0; i < q; i++) {
		query();
	}
}

// END MAIN CODE

Compilation message (stderr)

events.cpp: In function 'void file_io(std::string, std::string)':
events.cpp:30:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |   freopen(fi.c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:33:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |   freopen(fo.c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 30 / 30