Submission #577891

#	Time	Username	Problem	Language	Result	Execution time	Memory
577891		Markomafko972	Event Hopping (BOI22_events)	C++14	0 / 100	234 ms	23316 KiB

events

#include <bits/stdc++.h>
#define X first
#define Y second
using namespace std;

int n, q, a, b;
pair<int, int> p[100005];
vector< pair<int, int> > v;
set< pair<int, int> > s;
set< pair<int, int> > :: iterator it;
vector<int> sus[100005];
vector<int> roots;
int dub[100005];
int prt[20][100005];

bool cmp(pair<int, int> p1, pair<int, int> p2) {
	if (p1.X == p2.X) {
		if (p[p1.Y].X == p1.X) return true;
		else return false;
	}
	return p1.X < p2.X;
}

void rek(int x, int d) {
	dub[x] = d;
	
	for (int i = 0; i < sus[x].size(); i++) {
		prt[0][sus[x][i]] = x;
		rek(sus[x][i], d+1);
	}
}

int main () {
	
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	
	cin >> n >> q;
	for (int i = 0; i < n; i++) {
		cin >> p[i].X >> p[i].Y;
		v.push_back({p[i].X, i});
		v.push_back({p[i].Y, i});
	}
	
	sort(v.begin(), v.end(), cmp);
	
	for (int i = 0; i < v.size(); i++) {
		int ps = i;
		while (ps < v.size() && v[i].X == v[ps].X) ps++;
		for (int j = i; j < ps; j++) {
			if (v[j].X == p[v[j].Y].X) {
				s.insert({p[v[j].Y].Y, v[j].Y});
				//cout << "dodaj " << p[v[i].Y].Y << " " << v[i].Y << endl;
			}
			else {
				it = s.end();
				it--;
				
				//cout << v[i].Y+1 << " -> " << (it -> second)+1 << endl;
				if (v[j].Y != (it -> second)) sus[(it -> second)+1].push_back(v[j].Y+1);
				else roots.push_back(v[j].Y+1);
				//cout << "makni " << v[i].X << " " << v[i].Y << endl;
			}
		}
		
		for (int j = i; j < ps; j++) {
			if (v[j].X != p[v[j].Y].X) s.erase(v[j]);
		}
		i = ps-1;
	}
	
	for (int i = 0; i < roots.size(); i++) {
		rek(roots[i], 1);
	}
	
	for (int i = 1; i < 20; i++) {
		for (int j = 1; j <= n; j++) {
			prt[i][j] = prt[i-1][prt[i-1][j]];
		}
	}
	
	for (int i = 0; i < q; i++) {
		cin >> a >> b;
		int mini = dub[a]-dub[b];
		for (int j = 19; j >= 0; j--) {
			if (dub[prt[j][a]] >= dub[b]) a = prt[j][a];
		}
		
		if (a == b) cout << mini << "\n";
		else cout << "impossible\n";
	}
	
	return 0;
}

Compilation message (stderr)

events.cpp: In function 'void rek(int, int)':
events.cpp:27:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |  for (int i = 0; i < sus[x].size(); i++) {
      |                  ~~^~~~~~~~~~~~~~~
events.cpp: In function 'int main()':
events.cpp:47:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |  for (int i = 0; i < v.size(); i++) {
      |                  ~~^~~~~~~~~~
events.cpp:49:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |   while (ps < v.size() && v[i].X == v[ps].X) ps++;
      |          ~~~^~~~~~~~~~
events.cpp:72:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |  for (int i = 0; i < roots.size(); i++) {
      |                  ~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30