Submission #1315979

#TimeUsernameProblemLanguageResultExecution timeMemory
1315979vlomaczkEvent Hopping (BOI22_events)C++20
30 / 100
130 ms17404 KiB
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

int M = 100'000;
vector<pair<int, int>> seg(M);
int base = 1<<19;
vector<int> T(2*base, -1);

int zmaksuj(int a, int b) {
	if(a==-1) return b;
	if(b==-1) return a;
	if(seg[a].second < seg[b].second) return b;
	return a;
}

void update(int a, int b, int val) {
	if(a>b) return;
	if(a==b) T[a+base] = zmaksuj(T[a+base], val);
	a+=base-1;
	b+=base+1;
	while(a/2!=b/2) {
		if(a%2==0) T[a+1] = zmaksuj(T[a+1], val);
		if(b%2==1) T[b-1] = zmaksuj(T[b-1], val);
		a/=2; b/=2;
	}
}

int query(int x) {
	x += base;
	ll ans = -1;
	while(x>0) {
		ans = zmaksuj(ans, T[x]);
		x/=2;
	}
	return ans;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);

	int n, q;
	cin >> n >> q;
	ll inf = 1e9;
	int maxlog = 16;
	vector<vector<int>> jump(n, vector<int>(maxlog+1));
	vector<int> XY;
	for(int i=0; i<n; ++i) {
		cin >> seg[i].first >> seg[i].second;
		XY.push_back(seg[i].first);
		XY.push_back(seg[i].second);
	}
	sort(XY.begin(), XY.end());
	for(int i=0; i<n; ++i) {
		update(lower_bound(XY.begin(), XY.end(), seg[i].first) - XY.begin(), lower_bound(XY.begin(), XY.end(), seg[i].second) - XY.begin(), i);
		// update(seg[i].first, seg[i].second, i);
	}
	for(int i=0; i<n; ++i) {
		jump[i][0] = query(lower_bound(XY.begin(), XY.end(), seg[i].second) - XY.begin());
		// cout << i << ": " << jump[i][0] << "\n";
		// jump[i][0] = query(seg[i].second);
	}
	for(int j=1; j<=maxlog; ++j) {
		for(int i=0; i<n; ++i) {
			jump[i][j] = jump[jump[i][j-1]][j-1];
		}
	}
	while(q--) {
		int a, b;
		cin >> a >> b;
		--a;--b;
		if(a==b) {
			cout << "0\n";
			continue;
		}
		int res = 0;
		for(int i=maxlog; i>=0; --i) {
			// if(i>0 && jump[a][i]==jump[a][i-1]) continue;
			if(seg[jump[a][i]].second < seg[b].second) {
				res += 1<<i;
				a = jump[a][i];
			}
		}
		// cout << a << " " << res << " - " << jump[a][0] << "\n";
		if(seg[b].first <= seg[a].second && seg[a].second <= seg[b].second) cout << res+1 << "\n";
		else if(seg[b].first <= seg[jump[a][0]].second && seg[jump[a][0]].second <= seg[b].second) cout << res+2 << "\n";
		else cout << "impossible\n";
	}

	return 0;
}
#Verdict Execution timeMemoryGrader output
Fetching results...
#Verdict Execution timeMemoryGrader output
Fetching results...
#Verdict Execution timeMemoryGrader output
Fetching results...
#Verdict Execution timeMemoryGrader output
Fetching results...
#Verdict Execution timeMemoryGrader output
Fetching results...
#Verdict Execution timeMemoryGrader output
Fetching results...