Submission #840220

#	Time	Username	Problem	Language	Result	Execution time	Memory
840220		TranGiaHuy1508	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	18 ms	356 KiB

longesttrip

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

#include "longesttrip.h"

vector<int> subrange(vector<int> &V, int l, int r){
	vector<int> res(V.begin() + l, V.begin() + r + 1);
	return res;
}

vector<int> longest_trip(int N, int D){
	// Assuming D = 1

	vector<int> v1 = {0}, v2 = {1};

	for (int i = 2; i < N; i++){
		if (are_connected({v1.back()}, {i})) v1.push_back(i);
		else if (are_connected({v2.back()}, {i})) v2.push_back(i);
		else{
			reverse(v2.begin(), v2.end());
			v1.insert(v1.end(), v2.begin(), v2.end());
			v2.clear(); v2.push_back(i);
		}
	}

	if (are_connected({v1.front()}, {v2.front()})){
		reverse(v1.begin(), v1.end());
		v1.insert(v1.end(), v2.begin(), v2.end());
		return v1;
	}
	if (are_connected({v1.back()}, {v2.front()})){
		v1.insert(v1.end(), v2.begin(), v2.end());
		return v1;
	}
	if (are_connected({v1.front()}, {v2.back()})){
		v2.insert(v2.end(), v1.begin(), v1.end());
		return v2;
	}
	if (are_connected({v1.back()}, {v2.back()})){
		reverse(v1.begin(), v1.end());
		v2.insert(v2.end(), v1.begin(), v1.end());
		return v2;
	}

	if (!are_connected(v1, v2)){
		if (v1.size() > v2.size()) return v1;
		return v2;
	}

	int l1 = 0, r1 = v1.size() - 1;
	int l2 = 0, r2 = v2.size() - 1;

	while (l1 < r1){
		int mid = (l1 + r1) >> 1;
		bool edge = are_connected(subrange(v1, l1, mid), subrange(v2, l2, r2));
		if (edge) r1 = mid;
		else l1 = mid + 1;
	}

	while (l2 < r2){
		int mid = (l2 + r2) >> 1;
		bool edge = are_connected(subrange(v1, l1, r1), subrange(v2, l2, mid));
		if (edge) r2 = mid;
		else l2 = mid + 1;
	}

	vector<int> res1, res2;
	for (int i = l1; i < (int)v1.size(); i++) res1.push_back(v1[i]);
	for (int i = 0; i < l1; i++) res1.push_back(v1[i]);
	for (int i = l2; i < (int)v2.size(); i++) res2.push_back(v2[i]);
	for (int i = 0; i < l2; i++) res2.push_back(v2[i]);

	reverse(res1.begin(), res1.end());
	res2.insert(res2.begin(), res1.begin(), res1.end());
	return res2;
}

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 45 / 60