Submission #850090

#	Time	Username	Problem	Language	Result	Execution time	Memory
850090		Ahmed57	Event Hopping (BOI22_events)	C++17	100 / 100	471 ms	38908 KiB

events

#include <bits/stdc++.h>
using namespace std;
bool cmp(pair<pair<int,int>,int> a,pair<pair<int,int>,int> b){
    return a.first.second<b.first.second;
}
int P[100001][17],ind[100001];
pair<long long,long long> seg[800001];
void build(int p,int l,int r){
    if(l==r){
        seg[p] = {1e18,-1};
        return ;
    }
    int md = (l+r)/2;
    build(p*2,l,md);build(p*2+1,md+1,r);
    seg[p] = min(seg[p*2],seg[p*2+1]);
}
pair<long long,long long> query(int p,int l,int r,int lq,int rq){
    if(l>=lq&&r<=rq)return seg[p];
    if(r<lq||l>rq)return {1e18,-1};
    int md = (l+r)/2;
    return min(query(p*2,l,md,lq,rq),query(p*2+1,md+1,r,lq,rq));
}
void update(int p,int l,int r,int idx,pair<long long,long long> val){
    if(l==r){
        seg[p] = min(seg[p],val);
        return ;
    }
    int md = (l+r)/2;
    if(idx<=md)update(p*2,l,md,idx,val);
    else update(p*2+1,md+1,r,idx,val);
    seg[p] = min(seg[p*2],seg[p*2+1]);
}
signed main(){
    int n,q;cin>>n>>q;
    vector<pair<pair<long long,long long>,int>> v;
    map<int,int> comp,sav;
    for(int i = 0;i<n;i++){
        int a,b;
        cin>>a>>b;
        comp[a]++;comp[b]++;
        v.push_back({{a,b},i});
    }
    long long z = 0;
    for(auto i:comp){
        sav[i.first] = ++z;
    }
    for(int i = 0;i<n;i++){
        v[i].first.first = sav[v[i].first.first];
        v[i].first.second = sav[v[i].first.second];
    }
    sort(v.begin(),v.end());
    build(1,0,z);
    for(long long i = 0;i<v.size();i++){
        update(1,0,z,v[i].first.second,{v[i].first.first,i});
    }
    int in = 0;
    for(int i = 0;i<v.size();i++){
        ind[v[i].second] = i;
        P[i][0] = query(1,0,z,v[i].first.first,v[i].first.second).second;
        //cout<<P[i][0]<<" "<<v[i].first.first<<" "<<v[i].first.second<<endl;
    }
    for(int i = 0;i<n;i++){
        for(int j = 1;j<17;j++){
            P[i][j] = P[P[i][j-1]][j-1];
        }
    }
    while(q--){
        int a,b;cin>>a>>b;
        a--;b--;a = ind[a] , b = ind[b];
        if(a==b){
        cout<<0<<endl;
        continue;
        }else if(v[b].first.first<=v[a].first.second&&v[a].first.second<=v[b].first.second){
        cout<<1<<endl;
        continue;
        }
        int sum = 1 , cur = b;
        //cout<<cur<<endl;
        for(int i = 16;i>=0;i--){
            if(v[P[cur][i]].first.first>v[a].first.second){
                sum+=(1<<i);
                cur = P[cur][i];
            }
        }
        if(v[P[cur][0]].first.first<=v[a].first.second&&v[P[cur][0]].first.second>=v[a].first.second){
            cout<<sum+1<<endl;
        }else cout<<"impossible\n";
    }
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:53:26: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<std::pair<long long int, long long int>, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |     for(long long i = 0;i<v.size();i++){
      |                         ~^~~~~~~~~
events.cpp:57:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<std::pair<long long int, long long int>, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |     for(int i = 0;i<v.size();i++){
      |                   ~^~~~~~~~~
events.cpp:56:9: warning: unused variable 'in' [-Wunused-variable]
   56 |     int in = 0;
      |         ^~

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