Submission #862783

#	Time	Username	Problem	Language	Result	Execution time	Memory
862783		adhityamv	Event Hopping (BOI22_events)	C++17	0 / 100	70 ms	15048 KiB

events

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mp make_pair
const int ln=18;
int pow2[ln];
const int N=100000;
int st[N];
int en[N];
pair<int,int> seg[4*N];
void Build(int l,int r,int pos){
    if(l==r){
        seg[pos]=mp(st[l],l);
        return;
    }
    int mid=(l+r)/2;
    Build(l,mid,2*pos);
    Build(mid+1,r,2*pos+1);
    seg[pos]=min(seg[2*pos],seg[2*pos+1]);
}
pair<int,int> Query(int l,int r,int pos,int ql,int qr){
    if(ql>r || qr<l) return mp(1000000001,-1);
    if(ql<=l && qr>=r) return seg[pos];
    int mid=(l+r)/2;
    return min(Query(l,mid,2*pos,ql,qr),Query(mid+1,r,2*pos+1,ql,qr));
}
void solve(){
    int n,q;
    cin >> n >> q;
    vector<pair<pair<int,int>,int>> v;
    for(int i=0;i<n;i++){
        int s,e;
        cin >> s >> e;
        v.push_back(mp(mp(e,s),i));
    }
    sort(v.begin(),v.end());
    int rn[n];
    for(int i=0;i<n;i++) rn[v[i].second]=i;
    for(int i=0;i<n;i++){
        st[i]=v[i].first.second;
        en[i]=v[i].first.first;
    }
    int sparsetable[ln][n];
    Build(0,n-1,1);
    for(int i=0;i<n;i++){
        int si=lower_bound(en,en+n,st[i])-en;
        int ei=upper_bound(en,en+n,en[i])-en-1;
        int ind=si;
        for(int j=si;j<=ei;j++){
            if(st[j]<st[ind]) ind=j;
        }
        sparsetable[0][i]=ind;//Query(0,n-1,1,si,ei).second;
    }
    for(int k=0;k<ln-1;k++){
        for(int i=0;i<n;i++){
            sparsetable[k+1][i]=sparsetable[k][sparsetable[k][i]];
        }
    }
    while(q--){
        int u,v;
        cin >> u >> v;
        u--,v--;
        u=rn[u];
        v=rn[v];
        if(en[v]<en[u]){
            cout << "impossible" << "\n";
            return;
        }
        if(u==v){
            cout << 0 << "\n";
            continue;
        }
        if(st[v]<=en[u]){
            cout << 1 << "\n";
            continue;
        }
        int ans=0;
        for(int k=ln-1;k>=0;k--){
            if(st[sparsetable[k][v]]>en[u]){
                ans+=pow2[k];
                v=sparsetable[k][v];
            }
        }
        if(st[sparsetable[0][v]]<=en[u]){
            cout << ans+2 << "\n";
            continue;
        }
        /*int ans=1;
        while(v!=sparsetable[0][v]){
            v=sparsetable[0][v];
            ans++;
            if(st[v]<=en[u]) break;
        }
        if(st[v]<=en[u]) cout << ans << "\n";
        else*/ cout << "impossible" << "\n";
    }
}
int main(){
    pow2[0]=1;
    for(int i=0;i<ln-1;i++){
        pow2[i+1]=2*pow2[i];
    }
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    //cin >> t;
    t=1;
    while(t--) solve();
}

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