Submission #1011049

#	Time	Username	Problem	Language	Result	Execution time	Memory
1011049		Dan4Life	Longest Trip (IOI23_longesttrip)	C++17	85 / 100	15 ms	1112 KiB

longesttrip

#include "longesttrip.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)

bool connected(deque<int> A, deque<int> B){
	vector<int> Av,Bv;Av.clear(),Bv.clear();
	for(auto u : A) Av.pb(u);
	for(auto u : B) Bv.pb(u);
	return are_connected(Av,Bv);
}

vector<int> longest_trip(int N, int D){
	srand(time(0));
	
	deque<int> line1, line2; line1.clear(),line2.clear();
	vector<int> ord(N,0); iota(all(ord),0);
	random_shuffle(all(ord)); random_shuffle(all(ord));
	set<pair<int,int>> bad; bad.clear();
	for(auto x : ord){
		if(line1.empty()) line1.push_back(x);
		else if(line2.empty()) line2.push_back(x);
		else{
			int L1 = line1.back(), L2 = line2.back();
			if(!bad.count({min(L1,L2),max(L1,L2)}) and are_connected({L1},{L2})){
				reverse(all(line2));
				for(auto u : line2) line1.pb(u);
				line2.clear(); line2.push_back(x);
			}
			else{
				if(are_connected({x},{L1})) line1.pb(x);
				else line2.pb(x);
				bad.insert({min(L1,L2),max(L1,L2)});
			}
		}
	}
	vector<int> ans; ans.clear();
	if(line2.empty()){
		for(auto u : line1) ans.pb(u);
		return ans;
	}
	if(!connected(line1,line2)){
		if(sz(line1)<sz(line2)) swap(line1,line2);
		for(auto u : line1) ans.pb(u);
		return ans;
	}
	if(sz(line2)<2 or sz(line1)<2 or are_connected({line1[0],line1.back()},{line2[0],line2.back()})){
		if(are_connected({line1.back()},{line2.back()})){
			for(auto u : line1) ans.pb(u);
			reverse(all(line2));
			for(auto u : line2) ans.pb(u);
			return ans;
		}
		if(are_connected({line1.back()},{line2[0]})){
			for(auto u : line1) ans.pb(u);
			for(auto u : line2) ans.pb(u);
			return ans;
		}
		if(are_connected({line1[0]},{line2[0]})){
			reverse(all(line2));
			for(auto u : line2) ans.pb(u);
			for(auto u : line1) ans.pb(u);
			return ans;
		}
		if(are_connected({line1[0]},{line2.back()})){
			for(auto u : line2) ans.pb(u);
			for(auto u : line1) ans.pb(u);
			return ans;
		}
	}
	
	int l = 0, r = sz(line1)-1;
	while(l<r){
		int mid = (l+r)/2;
		deque<int> dq; dq.clear();
		for(int i = 0; i <= mid; i++) dq.pb(line1[i]);
		if(connected(dq,line2)) r=mid;
		else l=mid+1;
	}
	int x = l;
	l=0, r = sz(line2)-1;
	while(l<r){
		int mid = (l+r)/2;
		vector<int> v; v.clear();
		for(int i = 0; i <= mid; i++) v.pb(line2[i]);
		if(are_connected({line1[x]},v)) r=mid;
		else l=mid+1;
	}
	int y = l;
	for(int i = x+1; i<sz(line1); i++) ans.pb(line1[i]);
	for(int i = 0; i<=x; i++) ans.pb(line1[i]);
	for(int i = y; i < sz(line2); i++) ans.pb(line2[i]);
	for(int i = 0; i < y; i++) ans.pb(line2[i]);
    return ans;
}

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