Submission #1285446

#	Time	Username	Problem	Language	Result	Execution time	Memory
1285446		MMihalev	Longest Trip (IOI23_longesttrip)	C++20	100 / 100	7 ms	440 KiB

longesttrip

#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<random>
#include<tuple>
#include<chrono>
#include "longesttrip.h"
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//mt19937 rng(89356);
vector<int>ans;
int n;
int cntqueries=0;
bool edge(int u,int v)
{
    cntqueries++;
    return are_connected({u},{v});
}
void special(vector<int>nodes)
{
    if(!are_connected(nodes,ans))return;

    if(!edge(ans[0],ans.back()))
    {
        vector<int>nans;
        for(int x:nodes)nans.push_back(x);
        for(int i=0;i<ans.size();i++)
        {
            nans.push_back(ans[i]);
        }
        ans=nans;
        return;
    }

    int l=0,r=nodes.size()-1;
    int pnodes,pans;
    while(l<r)
    {
        int mid=(l+r)/2;
        vector<int>tmp;
        for(int i=l;i<=mid;i++)
        {
            tmp.push_back(nodes[i]);
        }
        if(are_connected(tmp,ans))
        {
            r=mid;
        }
        else l=mid+1;
    }
    pnodes=l;


    l=0;r=ans.size()-1;
    while(l<r)
    {
        int mid=(l+r)/2;
        vector<int>tmp;
        for(int i=l;i<=mid;i++)
        {
            tmp.push_back(ans[i]);
        }
        if(are_connected(tmp,{nodes[pnodes]}))
        {
            r=mid;
        }
        else l=mid+1;
    }
    pans=l;

    vector<int>nans;
    for(int i=pans+1;i<ans.size();i++)
    {
        nans.push_back(ans[i]);
    }
    for(int i=0;i<=pans;i++)
    {
        nans.push_back(ans[i]);
    }
    for(int i=pnodes;i<nodes.size();i++)
    {
        nans.push_back(nodes[i]);
    }
    for(int i=0;i<pnodes;i++)
    {
        nans.push_back(nodes[i]);
    }
    ans=nans;
}
void solve(vector<int>nodes,int u)//u=ans.back()
{
    if(nodes.size()==0)return;
    if(are_connected(nodes,{u})==0){special(nodes);return;}

    int l=0,r=nodes.size()-1;
    while(l<r)
    {
        int mid=(l+r)/2;
        vector<int>tmp;
        for(int i=l;i<=mid;i++)
        {
            tmp.push_back(nodes[i]);
        }
        if(are_connected(tmp,{u}))
        {
            r=mid;
        }
        else l=mid+1;
    }

    vector<int>other;
    int mid=(nodes.size()-1)/2;
    if(l<=mid)
    {
        for(int i=0;i<l;i++)other.push_back(nodes[i]);
        for(int i=l;i<nodes.size();i++)ans.push_back(nodes[i]);
        solve(other,ans.back());
    }
    else
    {
        for(int i=l;i>=0;i--)
        {
            ans.push_back(nodes[i]);
        }
        for(int i=l+1;i<nodes.size();i++)
        {
            other.push_back(nodes[i]);
        }
        solve(other,ans.back());
    }
}
std::vector<int> longest_trip(int N, int D)
{
    cntqueries=0;
    n=N;
    ans.clear();
    ///reset eveerything
    vector<int>v1,v2;

    vector<int>nodes;
    for(int i=0;i<n;i++)nodes.push_back(i);
    //shuffle(nodes.begin(),nodes.end(),rng);
    v1.push_back(nodes.back());nodes.pop_back();v2.push_back(nodes.back());nodes.pop_back();
    bool notconn=0;
    for(int i:nodes)
    {
        if(edge(i,v1.back()))
        {
            v1.push_back(i);
            notconn=0;
        }
        else if(notconn)
        {
            v2.push_back(i);
        }
        else if(edge(i,v2.back()))
        {
            v2.push_back(i);
            notconn=1;
        }
        else
        {
            vector<int>akka=v1;
            reverse(v2.begin(),v2.end());
            for(int x:v2)akka.push_back(x);
            v1=akka;
            v2.clear();v2.push_back(i);
            notconn=0;
        }
    }
    if(v1.size()>v2.size())
    {
        ans=v1;
        solve(v2,v1.back());
    }
    else
    {
        ans=v2;
        solve(v1,v2.back());
    }
    return ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 60 / 60