Submission #417271

#	Time	Username	Problem	Language	Result	Execution time	Memory
417271		kai824	Event Hopping 2 (JOI21_event2)	C++17	0 / 100	169 ms	125184 KiB

event2

//persistent segtree with lazy propagation?!?!?!
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define mp make_pair
#define eb emplace_back
#define pii pair<int,int>
#define f first
#define s second

pii vals[100005];
int lef[100005];

struct node{
  int s,e,v;//range sum persistent segtree :)
  node *l,*r;
  node(int ss=-1,int ee=-1){
    s=ss;e=ee;
    v=0;l=r=NULL;
    if(ss!=-1){//build whole thing for real...
      if(s==e)l=r=NULL;
      else{
        l=new node(s,(s+e)/2);
        r=new node((s+e)/2+1,e);
      }
    }
  }
  void copy(node *t){
    v=t->v;
    l=t->l;
    r=t->r;
    s=t->s;e=t->e;
  }
  void update(int p,node *t,int d){//copy t...
    copy(t);
    if(s==e){
      v+=d;
      return;
    }
    if(p<=(s+e)/2){
      l=new node();
      l->update(p,t->l,d);
    }else{
      r=new node();
      r->update(p,t->r,d);
    }
    v=l->v+r->v;
  }
  void upd(int p,int d){
    if(s==e){
      v+=d;return;
    }
    node *tmp=new node();
    if(p<=(s+e)/2){
      tmp->update(p,l,d);
      l=tmp;
    }else{
      tmp->update(p,r,d);
      r=tmp;
    }
    v=l->v+r->v;
  }
  int query(int a,int b){
    if(a<=s && e<=b)return v;
    int ans=0;
    if(a<=(s+e)/2)ans+=l->query(a,b);
    if((s+e)/2<b)ans+=r->query(a,b);
    return ans;
  }
} *st[100005];

vector<pii> v;int it;
void init_sts(int s,int e){//1, a
  v.clear();v.eb(s,0);
  st[s]=new node(1,e);
  for(int i=s+1;i<=e;i++){
    st[i]=new node();

    if(lef[i]<s)goto end;
    it=upper_bound(v.begin(),v.end(),mp(lef[i],LLONG_MAX))-v.begin()-1;
    it=v[it].s+1;
    if(v.back().s>it)goto end;
    if(v.back().s==it){
      st[i]->update(max(lef[i],lef[v.back().f]),st[i-1],1);
      st[i]->upd(lef[v.back().f],-1);
      if(lef[i]>lef[v.back().f])v.back().f=i;//push it to the back...
      continue;
    }
    st[i]->update(lef[i],st[i-1],1);
    v.eb(i,it);//increment at i...

    continue;
    end:;
    st[i]->copy(st[i-1]);
  }
}

int qq(int l,int r){
  return st[r]->query(l,r);
}

int32_t main(){
  ios_base::sync_with_stdio(false);cin.tie(0);
  int n,k,a,b;
  cin>>n>>k;

  vector<pii>disc;//discretisation: raw value, index...
  for(int i=0;i<n;i++){
    cin>>a>>b;
    disc.eb(a,i*2);
    disc.eb(b,i*2+1);
  }
  sort(disc.begin(),disc.end());
  a=1;
  for(int i=0;i<2*n;i++){
    if(i>0 && disc[i].f>disc[i-1].f)a++;
    if(disc[i].s&1)vals[disc[i].s/2].s=a;
    else vals[disc[i].s/2].f=a;
  }
  for(int i=0;i<n;i++){
    //cout<<vals[i].f<<' '<<vals[i].s<<'\n';
    lef[vals[i].s]=max(lef[vals[i].s],vals[i].f);//both should be discretised...
  }
  init_sts(1,a);//initialise segtrees...

  int cur=qq(1,a),tmp;
  if(cur<k){
    cout<<-1;
    return 0;
  }//else cout<<cur<<'\n';
  set<pii> ss;ss.insert(mp(1,1));ss.insert(mp(a,a));
  set<pii>::iterator it,it2;
  bool mk[n];memset(mk,0,sizeof(mk));
  for(int i=0;i<n;i++){
    it=ss.lower_bound(vals[i]);
    it2=it--;
    if(it2==ss.end())continue;
    if(it->s<=vals[i].f && vals[i].s<=it2->f){
      tmp=cur;
      tmp+=1+(qq(it->s,vals[i].f)+qq(vals[i].s,it2->f) ) - qq(it->s,it2->f);
      if(tmp>=k){
        mk[i]=true;
        cur=tmp;
        ss.insert(vals[i]);
      }
    }
  }
  int cnt=0;
  for(int i=0;i<n && cnt<k;i++){
    if(mk[i]){
      cout<<i+1<<'\n';
      cnt++;
    }
  }
  return 0;
}
/*
5 4
1 3
2 5
8 9
6 8
10 15
*/

• Subtask 1: 0 / 7
• Subtask 2: 0 / 1
• Subtask 3: 0 / 31
• Subtask 4: 0 / 61