Submission #660095

#	Time	Username	Problem	Language	Result	Execution time	Memory
660095		Karuk	Event Hopping (BOI22_events)	C++14	20 / 100	192 ms	29624 KiB

events

#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
pair<int,int>max(pair<int,int>a,pair<int,int>b) {
    return a>b?a:b;
}
const int k=(1<<30);
int main() {
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    int n,q;cin>>n>>q;
    pair<int,int>a[n];
    pair<int,int> prev[n][25];
    vector<pair<pair<int,int>,int>>v;
    for(int i=0;i<n;i++) {
        int x,y;
        cin>>x>>y;
        a[i]={x,y};
        v.push_back({{x,1},i});
        v.push_back({{y,2},i});
    }
    sort(v.begin(),v.end());
    set<pair<int,int>>smalleststart;
    for(auto i:v) {
        if(i.first.second==2) {
            smalleststart.erase({a[i.second].first,i.second});
        } else {
                smalleststart.insert({i.first.first,i.second});
                prev[i.second][0]=(*smalleststart.begin());
        }
    }
    ///coord1,isbeginning,index
    for(int j=1;j<25;j++) {
        for(int i=0;i<n;i++) {
            prev[i][j]=prev[prev[i][j-1].second][j-1];
        }
    }
    for(int i=0;i<q;i++) {
        int x,y;cin>>x>>y;x--;y--;
        if(x==y)cout<<0<<endl;
        else if(a[x].second>=a[y].first && a[x].second<=a[y].second)cout<<1<<endl;
        else if(a[x].second>a[y].second){cout<<"impossible"<<endl;}
        else {
            int cnt=0;
            int cur=y;
            int en=a[x].second;
            for(int j=24;j>=0;j--) {
                if(prev[cur][j].first>en) {
                    cur=prev[cur][j].second;
                    cnt+=(1<<j);
                }
            }
            if(prev[cur][0].first>en)cout<<"impossible"<<endl;
            else cout<<cnt+2<<endl;
        }
    }
    return 0;
}
///9:30

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