Submission #577732

#	Time	Username	Problem	Language	Result	Execution time	Memory
577732		dorijanlendvaj	Event Hopping (BOI22_events)	C++14	100 / 100	220 ms	12608 KiB

events

#include <bits/stdc++.h>
#define x first
#define y second
#define pii pair<int,int>
using namespace std;
using ll=long long;
#define pll pair<ll,ll>
#define vi vector<int>
#define vl vector<ll>
#define pb push_back
#define eb emplace_back
#define all(a) begin(a),end(a)

const int N=100010,MOD=1e9+7,M=1<<17;
const char en='\n';
const ll LLINF=1ll<<60;

int n,q,l[N],r[N],par[20][N];
pii seg[M*2+10];

pii ge(int l,int r,int lo=0,int hi=M,int i=1)
{
	if (lo>=l && hi<=r) return seg[i];
	if (lo>=r || hi<=l) return {MOD,MOD};
	int mid=(lo+hi)/2;
	return min(ge(l,r,lo,mid,i*2),ge(l,r,mid,hi,i*2+1));
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	for (int i=0;i<2*M;++i) seg[i]={MOD,MOD};
	cin>>n>>q;
	vector<pair<pii,int>> v;
	for (int i=0;i<n;++i)
	{
		cin>>l[i]>>r[i];
		v.pb({{r[i],l[i]},i});
	}
	sort(all(v));
	for (int i=0;i<n;++i) seg[i+M]={v[i].x.y,v[i].y};
	for (int i=M-1;i;--i) seg[i]=min(seg[i*2],seg[i*2+1]);
	for (int i=0;i<n;++i)
	{
		int poc=lower_bound(all(v),pair<pii,int>(pii(l[i],0),0))-v.begin();
		int kr=lower_bound(all(v),pair<pii,int>(pii(r[i],MOD),MOD))-v.begin();
		pii re=ge(poc,kr);
		par[0][i]=re.y;
		//cout<<i<<' '<<re.y<<en;
	}
	for (int j=0;j<17;++j)
	{
		for (int i=0;i<n;++i) par[j+1][i]=par[j][par[j][i]];
	}
	while (q--)
	{
		int a,b;
		cin>>a>>b;
		--a;
		--b;
		if (a==b)
		{
			cout<<0<<en;
			continue;
		}
		if (r[a]>r[b])
		{
			cout<<"impossible\n";
			continue;
		}
		int an=0;
		for (int j=17;j>=0;--j) if (l[par[j][b]]>r[a]) an+=1<<j,b=par[j][b];
		if (l[b]>r[a]) ++an,b=par[0][b];
		if (l[b]>r[a])
		{
			cout<<"impossible\n";
			continue;
		}
		cout<<an+1<<en;
	}
}

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