Submission #603852

#	Time	Username	Problem	Language	Result	Execution time	Memory
603852		Evirir	Event Hopping (BOI22_events)	C++17	0 / 100	966 ms	104232 KiB

events

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#define watch(x) cout<<(#x)<<"="<<(x)<<'\n'
#define mset(d,val) memset(d,val,sizeof(d))
#define cbug if(DEBUG) cout
#define setp(x) cout<<fixed<<setprecision(x)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define forn(i,a,b) for(int i=(a);i<(b);i++)
#define fore(i,a,b) for(int i=(a);i<=(b);i++)
#define pb push_back
#define F first
#define S second
#define fbo find_by_order
#define ook order_of_key
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
//template<typename T>
//using pbds = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
void SD(int t=0){ cout<<"PASSED "<<t<<endl; }
ostream& operator<<(ostream &out, ii x){ out<<"("<<x.F<<","<<x.S<<")"; return out; }
template<typename T> void amax(T &a, T b){ a=max(a,b); }
template<typename T> void amin(T &a, T b){ a=min(a,b); }
const ll INF = ll(1e18);
const int MOD = 998244353;

class PointSegmentTree{
private:
	int size_;
	vector<int> v;
	void update(int p, int val, int k, int l, int r)
	{
		if(p < l || r < p) return;
		if(l == r){
			v[k]=val;	//modification
			return;
		}
		int mid = (l+r)>>1;
		update(p, val, k*2, l, mid);
		update(p, val, k*2+1, mid+1, r);
		v[k] = merge(v[k*2], v[k*2+1]);
	}
	int query(int s, int e, int k, int l, int r)
	{
		if(e < l || r < s) return 0; //dummy value
		if(s <= l && r <= e) return v[k];
		int mid = (l+r)>>1;
		int lc = query(s, e, k*2, l, mid);
		int rc = query(s, e, k*2+1, mid+1, r);
		return merge(lc, rc);
	}
	
public:
	PointSegmentTree(): v(vector<int>()) {}
	PointSegmentTree(int n){
		for(size_=1;size_<n;) size_<<=1;
		v.resize(size_*4);
	}
	//void reset(){}
	inline int merge(int x, int y){
		return max(x, y);
	}
	inline void update(int p, int val){
		update(p, val, 1, 0, size_-1);
	}
	inline int query(int l, int r){
		return query(l, r, 1, 0, size_-1);
	}
};

const bool DEBUG = 0;
const int MAXN = 100005;
const int MAXA = MAXN * 2;
const int LG = 20;

int n,Q;
int s[MAXN], e[MAXN];  //reversed
vii a,q,q0;
int nxt[MAXA][LG];
PointSegmentTree st[LG];

vi comp;
int getid(int x){ return sz(comp) - 1 - (lower_bound(all(comp), x) - comp.begin()); }

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	mset(nxt,-1);

	cin>>n>>Q;
	forn(i,0,n)
	{
		cin>>e[i]>>s[i];
		comp.pb(s[i]);
		comp.pb(e[i]);
		a.pb({s[i], e[i]});
	}
	forn(z,0,Q)
	{
		int u,v; cin>>u>>v; u--; v--;
		q0.pb({v, u});
		q.pb({s[v], s[u]});
	}

	// compress everything in reverse
	sort(all(comp));
	forn(i,0,n)
	{
		s[i]=getid(s[i]);
		e[i]=getid(e[i]);
		a[i]={getid(a[i].F), getid(a[i].S)};
	}
	forn(i,0,Q) q[i]={getid(q[i].F), getid(q[i].S)};

	forn(i,0,MAXA) forn(j,0,LG) nxt[i][j]=i;
	forn(i,0,n) amax(nxt[s[i]][0], e[i]);
	forn(i,0,LG) st[i]=PointSegmentTree(MAXA);
	
	forn(i,0,MAXA) st[0].update(i, nxt[i][0]);

	for(int i=MAXA-1;i>=0;i--)
	{
		forn(j,1,LG)
		{
			nxt[i][j] = st[j-1].query(i, nxt[i][j-1]);
			st[j].update(i, nxt[i][j]);
		}
	}
	
	forn(z,0,Q)
	{
		if(q0[z].F==q0[z].S)
		{
			cout<<0<<'\n';
			continue;
		}
		if(e[q0[z].F]>e[q0[z].S])
		{
			cout<<"impossible\n";
			continue;
		}

		int u=q[z].F, v=q[z].S;
		int ans=0;
		for(int j=LG-1;j>=0;j--)
		{
			if(nxt[u][j]<v)
			{
				u=nxt[u][j];
				ans+=(1<<j);
			}
		}
		u=nxt[u][0];
		ans++;
		if(u>=v) cout<<ans<<'\n';
		else cout<<"impossible\n";
	}
	
	return 0;
}

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