Submission #1140484

#	Time	Username	Problem	Language	Result	Execution time	Memory
1140484		Luvidi	Longest Trip (IOI23_longesttrip)	C++20	60 / 100	339 ms	776 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

vector<int> f(int x,vector<int> v){
    if(v.empty())return {x};
    int idx=rng();
    idx=abs(idx)%v.size();
    vector<int> v1,v2;
    for(int i=0;i<v.size();i++)if(i!=idx){
        if(are_connected({v[idx]},{v[i]}))v1.push_back(v[i]);
        else v2.push_back(v[i]);
    }
    v1=f(v[idx],v1);
    v1.push_back(x);
    for(int i:v2)v1.push_back(i);
    return v1;
}

std::vector<int> longest_trip(int n, int d)
{
    vector<int> v1,v2;
    int idx=rng();
    idx=abs(idx)%n;
    for(int i=0;i<n;i++)if(i!=idx){
        if(are_connected({idx},{i}))v1.push_back(i);
        else v2.push_back(i);
    }
    v1=f(idx,v1);
    if(v2.empty())return v1;
    bool b1=are_connected({v1[0]},v2),b2=are_connected({v1.back()},v2);
    if(b1)reverse(v1.begin(),v1.end());
    if(b1||b2){
        int l=0,r=v2.size();
        while(l<r){
            int m=(l+r)/2;
            vector<int> v;
            for(int i=0;i<=m;i++)v.push_back(v2[i]);
            if(are_connected({v1.back()},v))r=m;
            else l=m+1;
        }
        v1.push_back(v2[l]);
        for(int j:v2)if(v2[l]!=j)v1.push_back(j);
        return v1;
    }else if(are_connected(v1,v2)){
        int l=0,r=v1.size()-1;
        while(l<r){
            int m=(l+r)/2;
            vector<int> v;
            for(int i=0;i<=m;i++)v.push_back(v1[i]);
            if(are_connected(v,v2))r=m;
            else l=m+1;
        }
        int idx=l;
        l=0,r=v2.size()-1;
        while(l<r){
            int m=(l+r)/2;
            vector<int> v;
            for(int i=0;i<=m;i++)v.push_back(v2[i]);
            if(are_connected({v1[idx]},v))r=m;
            else l=m+1;
        }
        vector<int> ans;
        for(int k=idx+1;k<v1.size();k++)ans.push_back(v1[k]);
        for(int k=0;k<=idx;k++)ans.push_back(v1[k]);
        ans.push_back(v2[l]);
        for(int k:v2)if(v2[l]!=k)ans.push_back(k);
        return ans;
    }
    if(v1.size()>v2.size())return v1;
    return v2;
}

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 20 / 60