Submission #577692

#	Time	Username	Problem	Language	Result	Execution time	Memory
577692		vanic	Event Hopping (BOI22_events)	C++14	25 / 100	1302 ms	203920 KiB

events

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <cstring>
#include <queue>

using namespace std;

const int maxn=5005, Log=14, pot=(1<<Log);

vector < int > svi;

void query(int L, int D, int x, int l, int d){
	if(L>=l && D<=d){
		svi.push_back(x);
		return;
	}
	if((L+D)/2>=l){
		query(L, (L+D)/2, x*2, l, d);
	}
	if((L+D)/2+1<=d){
		query((L+D)/2+1, D, x*2+1, l, d);
	}
}


pair < int, int > a[maxn];
set < int > s;
map < int, int > m;
int dist[pot*2];
int d[maxn];
vector < pair < int, int > >  ms[pot*2];
int ok[maxn][maxn];

void precompute(){
	for(int i=2; i<pot*2; i++){
		ms[i].push_back({i/2, 0});
	}
}

void bfs(int x){
	memset(dist, -1, sizeof(dist));
	memset(d, -1, sizeof(d));
	queue < int > q1, q2;
	q1.push(a[x].second+pot);
	dist[a[x].second+pot]=0;
	d[x]=0;
	int tren=0;
	while(!q1.empty()){
		while(!q1.empty()){
			x=q1.front();
			q1.pop();
			for(int i=0; i<(int)ms[x].size(); i++){
				if(ms[x][i].second){
					if(dist[ms[x][i].first]==-1){
						dist[ms[x][i].first]=tren+1;
						q2.push(ms[x][i].first);
					}
					if(d[ms[x][i].second]==-1){
						d[ms[x][i].second]=tren+1;
					}
				}
				else{
					if(dist[ms[x][i].first]==-1){
						dist[ms[x][i].first]=tren;
						q1.push(ms[x][i].first);
					}
				}
			}
		}
		swap(q1, q2);
		tren++;
	}
}

int main(){
	memset(ok, -1, sizeof(ok));
	precompute();
	int n, q;
	scanf("%d%d", &n, &q);
	for(int i=1; i<=n; i++){
		scanf("%d%d", &a[i].first, &a[i].second);
		s.insert(a[i].first);
		s.insert(a[i].second);
	}
	int br=0;
	for(auto it=s.begin(); it!=s.end(); it++){
		m[*it]=br;
		br++;
	}
	for(int i=1; i<=n; i++){
		a[i]={m[a[i].first], m[a[i].second]};
//		cout << a[i].first << ' ' << a[i].second << endl;
		query(0, pot-1, 1, a[i].first, a[i].second);
		while(!svi.empty()){
//			cout << "moji " << svi.back() << endl;
			ms[svi.back()].push_back({a[i].second+pot, i});
			svi.pop_back();
		}
	}
	int x, y;
	for(int i=0; i<q; i++){
		scanf("%d%d", &x, &y);
		if(ok[x][x]==-1){
			bfs(x);
			for(int j=1; j<=n; j++){
				ok[x][j]=d[j];
			}
		}
		if(ok[x][y]==-1){
			printf("impossible\n");
		}
		else{
			printf("%d\n", ok[x][y]);
		}
	}
	return 0;
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:83:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |  scanf("%d%d", &n, &q);
      |  ~~~~~^~~~~~~~~~~~~~~~
events.cpp:85:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |   scanf("%d%d", &a[i].first, &a[i].second);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:106:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  106 |   scanf("%d%d", &x, &y);
      |   ~~~~~^~~~~~~~~~~~~~~~

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