제출 #601083

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
601083		CSQ31	Event Hopping (BOI22_events)	C++17	25 / 100	1580 ms	4040 KiB

events

#include <bits/stdc++.h>
using namespace std;
#define all(a) a.begin(),a.end()
#define owo ios_base::sync_with_stdio(0);cin.tie(0);
const int MAXN = 1e5+1;
int s[MAXN],e[MAXN];
//fuck binlift how
//p(k,i) = min s if we jump backwards 2^k times
//p(k-1,i) = min of p(k-1),i<= x <= i ,p(k-1,x)
//yeesh but this n log^2n
//should pass maybe?
//1e5 * 18 * 18 = 3e7
int p[19][MAXN];
int main()
{
	owo
	int n,q;
	cin>>n>>q;
	vector<int>crd;
	for(int i=0;i<n;i++)cin>>s[i]>>e[i];
	for(int i=0;i<n;i++){
		crd.push_back(s[i]);
		crd.push_back(e[i]);
	}
	sort(all(crd));
	crd.resize(unique(all(crd)) - crd.begin());
	for(int i=0;i<n;i++){
		s[i] = lower_bound(all(crd),s[i]) - crd.begin()+1;
		e[i] = lower_bound(all(crd),e[i]) - crd.begin()+1;
	}
	//int m = crd.size();
	for(int i=0;i<n;i++){
		p[0][i] = i;
		for(int j=0;j<n;j++){
			if(s[i] <= e[j] && e[j] <= e[i]){
				if(s[j] < s[p[0][i]])p[0][i] = j;
			}	
		}
	}
	while(q--){
		int l,r;
		cin>>l>>r;
		l--;
		r--;
		if(l==r){
			cout<<0<<'\n';
			continue;
		}
		if(e[l] > e[r]){
			cout<<"impossible"<<'\n';
			continue;
		}
		int ans = 1;
		while(s[r] > e[l]){
			if(p[0][r] == r){
				ans = -1;
				break;
			}
			ans++;
			r = p[0][r];
		}
		if(ans==-1)cout<<"impossible"<<'\n';
		else cout<<ans<<'\n';
	}
	
	
}

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