Submission #852234

#	Time	Username	Problem	Language	Result	Execution time	Memory
852234		Wansur	Longest Trip (IOI23_longesttrip)	C++17	15 / 100	14 ms	1816 KiB

longesttrip

#include <vector>
#include<bits/stdc++.h>
#define f first
#define s second
#define ent '\n'

using namespace std;
typedef long long ll;

const int mx=5e2+12;

vector<int> g[mx];
int was[mx][mx];

bool are_connected(std::vector<int> A, std::vector<int> B);

int  ask(int a,int b){
	if(!was[a][b]){
		was[a][b]=was[b][a]=(int)are_connected({a},{b})+1;
	}
	return was[a][b]-1;
}

std::vector<int> longest_trip(int n, int d){
	vector<int> ans;
	if(d==3){
		for(int i=0;i<n;i++){
			ans.push_back(i);
		}
		return ans;
	}
	bool used[n+12]={};
	if(d==2){
		deque<int> ans;
		ans.push_back(0);
		for(int i=1;i<n;i++){
			if(are_connected({0},{i})){
				ans.push_back(i);
				used[0]=1;
				used[i]=1;
				break;
			}
		}
		for(int i=1;i<n;i++){
			if(used[i]){
				continue;
			}
			if(are_connected({ans.back()},{i})){
				ans.push_back(i);
			}
			else{
				ans.push_front(i);
			}
		}
		vector<int> v;
		for(int x:ans){
			v.push_back(x);
		}
		return v;
	}
	for(int i=0;i<n;i++){
		g[i].clear();
		for(int j=0;j<n;j++){
			was[i][j]=0;
		}
	}
	srand(time(0));
	vector<int> t;
	for(int i=0;i<n;i++){
		g[i].push_back(i);
		t.push_back(i);
	}
	while(t.size()>2){
		int a=t[0],b=t[1],c=t[2];
		vector<pair<int,int>> d;
		d.push_back({a,b});
		d.push_back({a,c});
		d.push_back({b,c});
		random_shuffle(d.begin(),d.end());
		int v,u;
		if(ask(d[0].f,d[0].s)){
			v=d[0].f,u=d[0].s;
		}
		else if(ask(d[1].f,d[1].s)){
			v=d[1].f,u=d[1].s;
		}
		else{
			v=d[2].f,u=d[2].s;
		}
		reverse(g[v].begin(),g[v].end());
		for(int x:g[u]){
			g[v].push_back(x);
		}
		g[u].clear();
		int x=g[v][0];
		if(x!=v){
			for(int to:g[v]){
				g[x].push_back(to);
			}
			g[v].clear();
		}
		t.clear();
		for(int i=0;i<n;i++){
			if((int)g[i].size()>0){
				t.push_back(i);
			}
		}
	}
	int a=t[0],b=t[1];
	if(are_connected(g[a],g[b])){
		vector<int> ans;
		if(ask(g[a][0],g[b][0])){
			reverse(g[a].begin(),g[a].end());
			for(int x:g[a]){
				ans.push_back(x);
			}
			for(int x:g[b]){
				ans.push_back(x);
			}
		}
		else if(ask(g[a].back(),g[b][0])){
			for(int x:g[a]){
				ans.push_back(x);
			}
			for(int x:g[b]){
				ans.push_back(x);
			}
		}
		else if(ask(g[a][0],g[b].back())){
			for(int x:g[b]){
				ans.push_back(x);
			}
			for(int x:g[a]){
				ans.push_back(x);
			}
		}
		else{
			if(ask(g[a].back(),g[b].back())==0){
				assert(0);
			}
			reverse(g[b].begin(),g[b].end());
			for(int x:g[a]){
				ans.push_back(x);
			}
			for(int x:g[b]){
				ans.push_back(x);
			}
		}
		return ans;
	}
	else{
		if((int)g[a].size()>(int)g[b].size()){
			return g[a];
		}
		else{
			return g[b];
		}
	}
}

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