Submission #1213711

#	Time	Username	Problem	Language	Result	Execution time	Memory
1213711		Warinchai	Exam (eJOI20_exam)	C++20	13 / 100	35 ms	25160 KiB

exam

#include<bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
int a[200005];
int b[200005];
vector<int>id[200005];
vector<int>v;
vector<pair<int,int>>op;
int n;

struct fenwick{
    int info[100005];
    void upd(int id,int val){
        for(int i=id;i<=n;i+=i&-i)info[i]=max(info[i],val);
    }
    int fans(int id){
        int ans=0;
        for(int i=id;i>0;i-=i&-i)ans=max(ans,info[i]);
        return ans;
    }
}fw;

int qr[5005][5005];
int dp[5005];
int mx[20][100005];
int lg[100005];

int fmx(int l,int r){
    int x=lg[r-l+1];
    //cerr<<"qr:"<<l<<' '<<r<<" "<<max(mx[x][l],mx[x][r-(1<<x)])<<"\n";
    return max(mx[x][l],mx[x][r-(1<<x)]);
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++)cin>>a[i],v.push_back(a[i]);
    for(int i=1;i<=n;i++)cin>>b[i],v.push_back(b[i]);
    sort(v.begin(),v.end());
    v.erase(unique(v.begin(),v.end()),v.end());
    for(int i=1;i<=n;i++){
        int x=lower_bound(v.begin(),v.end(),a[i])-v.begin()+1;
        a[i]=x;
        x=lower_bound(v.begin(),v.end(),b[i])-v.begin()+1;
        b[i]=x;
    }
    for(int i=1;i<=n;i++){
        id[a[i]].push_back(i);
    }
    for(int i=1;i<=n;i++)mx[0][i]=a[i];
    for(int i=1;i<20;i++)for(int j=1;j<=n;j++){
        mx[i][j]=max(mx[i-1][j],mx[i-1][min(n,j+(1<<(i-1)))]);
    }
    lg[1]=0;
    for(int i=2;i<=n;i++)lg[i]=lg[i/2]+1;
    for(int i=1;i<=n;i++){
        vector<pair<int,int>>top;
        for(auto x:id[b[i]]){
            int mx=fmx(min(i,x),max(i,x));
            if(mx>b[i])continue;
            if(n<=5000){
                qr[i][x]=1;
            }
            top.push_back({i,x});
        }
        for(auto x:top)op.push_back(x);
    }
    //sort(op.begin(),op.end());
    if(n<=5000){
        for(int i=1;i<=n;i++){
            int mx=0;
            for(int j=1;j<=n;j++){
                mx=max(mx,dp[j]);
                if(qr[i][j]==1){
                    dp[j]=mx+1;
                }
            }
        }
        int ans=0;
        for(int i=1;i<=n;i++)ans=max(ans,dp[i]);
        cout<<ans;
        return 0;
    }

    int ans=0;
    for(auto [x,y]:op){
        //cerr<<x<<" "<<-y<<"\n";
        int val=fw.fans(y)+1;
        ans=max(ans,val);
        //cerr<<val<<"\n";
        fw.upd(y,val);
    }
    cout<<ans;
}

• Subtask 1: 0 / 14
• Subtask 2: 0 / 12
• Subtask 3: 13 / 13
• Subtask 4: 0 / 23
• Subtask 5: 0 / 16
• Subtask 6: 0 / 22