Submission #605049

#	Time	Username	Problem	Language	Result	Execution time	Memory
605049		l_reho	Event Hopping (BOI22_events)	C++14	10 / 100	1600 ms	524288 KiB

events

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

int N, Q;
vector<ll> S, E;
vector<array<ll, 3>> ranges;

vector<vector<ll>> dist;

void solve(){
	cin>>N>>Q;
	
	S.assign(N, 0);
	E.assign(N, 0);
	ranges.assign(N, array<ll, 3>());
	dist.assign(N, vector<ll>(N, INT_MAX));
	// graph.assign(N, vector<int>());
	
	
	for(int i = 0; i < N; i++){
		int s, e;
		cin>>s>>e;
		
		S[i] = s;
		E[i] = e;
		
		ranges[i] = {s, e, i};
	}
	
	sort(ranges.begin(), ranges.end(), [&](array<ll, 3> a, array<ll, 3> b){
		return a[1] > b[1];
	});
	
	
	
	for(int q = 0; q < Q; q++){
		int sq, eq;
		cin>>sq>>eq;
		sq--;
		eq--;
		queue<int> que;
		que.push(sq);
		dist[sq][sq] = 0;
		while(!que.empty()){
			int curr = que.front();
			
			que.pop();
			
			// vector<int> adj = graph[curr];
			// cerco il primo nodo tale che end di quel nodo è < se
			// posso trovarlo in O(logn)
			
			int node = -1;
			for(int j = 0; j < N; j++){
				if(dist[sq][ranges[j][2]] == INT_MAX &&  ranges[j][0] <= E[curr] && ranges[j][1] >= E[curr] && ranges[j][1] <= E[eq]) {
					node = ranges[j][2];
					if(node != -1){
						dist[sq][node] = dist[sq][curr] +1;
						que.push(node);
					}
				}
			}
			
		
			
			/*
			for(int a : adj){
				if(dist[sq][a] != INT_MAX) continue;
				
				dist[sq][a] = dist[sq][curr]+1;
				que.push(a);
			}
			*/
		}
		if(dist[sq][eq] == INT_MAX)
			cout<<"impossible"<<endl;
		else cout<<dist[sq][eq]<<endl;
		
	}
	
	
}
 
int main(){
	solve();
	return 0;
}

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