Submission #805399

#	Time	Username	Problem	Language	Result	Execution time	Memory
805399		vjudge1	Event Hopping (BOI22_events)	C++17	30 / 100	286 ms	43260 KiB

events

#include<bits/stdc++.h>
using namespace std;
#define all(fl) fl.begin(),fl.end()
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=j;i<=k;i++)
#define for2(i,j,k) for(int i=j;i>=k;i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pli pair<long long,int>
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
const int maxn=1e5+9;
pii a[maxn];
int ans[maxn];
int st[maxn][19];
int n,q;
vector<int>add[maxn*2],del[maxn*2];
void build(){
multiset<pii>t;
multiset<pii>::iterator it;
for1(i,1,n){
add[a[i].se].pb(i);
del[a[i].fi].pb(i);
}
for2(i,2*n,1){
for (auto v:add[i]){
    t.insert({a[v].se,v});
}
for (auto v:add[i]){
    it=t.end();
    it--;
    auto tmp=(*it);
    if (tmp.fi<=a[v].se)continue;
    st[v][0]=tmp.se;
}
for (auto v:del[i]){
    t.erase({a[v].se,v});
}
vector<int>().swap(add[i]);
vector<int>().swap(del[i]);
}
for1(j,1,18){
for1(i,1,n){
st[i][j]=st[st[i][j-1]][j-1];
}
}
}
int b[maxn];
vector<int>query[maxn];
void solveright(){
multiset<pii>t;
multiset<pii>::iterator it;
for1(i,1,n){
add[a[i].se].pb(i);
del[a[i].fi].pb(i);
}
for2(i,2*n,1){
for (auto v:add[i]){
    t.insert({a[v].se,v});
}
for (auto v:add[i]){
    for (auto u:query[v]){
        int id=u;
        int e=b[id];
        it=t.lower_bound({a[e].fi,0});
        if (it==t.end()){
            ans[id]=-1;
            continue;
        }
        auto tmp=(*it);
        if (tmp.fi>a[e].se){
            ans[id]=-1;
            continue;
        }
        ans[id]+=2;
    }
}
for (auto v:del[i]){
    t.erase({a[v].se,v});
}
vector<int>().swap(add[i]);
vector<int>().swap(del[i]);
}
}
signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    //freopen(".INP","r",stdin);
    //freopen(".OUT","w",stdout);
    cin>>n>>q;
    vector<int>nen;
    nen.pb(0);
    for1(i,1,n){
    cin>>a[i].fi>>a[i].se;
    nen.pb(a[i].fi);
    nen.pb(a[i].se);
    }
    sort(all(nen));
    map<int,int>n1;
    for1(i,1,sz(nen)-1){
    if (nen[i]==nen[i-1])continue;
    n1[nen[i]]=n1[nen[i-1]]+1;
    }
    for1(i,1,n){
    a[i].fi=n1[a[i].fi];
    a[i].se=n1[a[i].se];
    //cout<<"type "<<" "<<a[i].fi<<" "<<a[i].se<<'\n';
    }
    build();
    for1(i,1,q){
    int s,e;
    cin>>s>>e;
    if (s==e)continue;
    if (a[s].se>a[e].se){
        ans[i]=-1;
        continue;
    }
    for2(j,18,0){
    if (!st[s][j])continue;
    int id=st[s][j];
    if (a[id].se<a[e].fi){
        ans[i]+=(1<<j);
        s=id;
        //cout<<s<<'\n';
    }
    }
    if (a[s].se>=a[e].fi){
        ans[i]++;
        continue;
    }
    //cout<<a[st[1][0]].se<<" "<<a[e].fi<<'\n';
    b[i]=e;
    query[s].pb(i);
    }
    solveright();
    for1(i,1,q){
    if (ans[i]==-1)cout<<"impossible"<<'\n';
    else cout<<ans[i]<<'\n';
    }
}

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