Submission #217368

#	Time	Username	Problem	Language	Result	Execution time	Memory
217368		vanic	Cover (COCI18_cover)	C++14	120 / 120	8 ms	768 KiB

cover

#include <iostream>
#include <cstdio>
#include <math.h>
#include <algorithm>
#include <vector>
#include <set>
/*
#include <dora>
#include <vito>
*/
#include <map>
#include <queue>
using namespace std;
typedef long long ll;
 
const int maxn=5005;
const ll inf=1e18;
 
int n;
map < pair < int, int >, bool > bio;
vector < pair < int, int > > v;
deque < pair < int, int > > q;
ll dp[maxn];
vector < pair < ll, ll > > ljusk;

bool ccw(pair < ll, ll > a, pair < ll, ll > b, pair < ll, ll > c){
	return a.first*(b.second-c.second)+b.first*(c.second-a.second)+c.first*(a.second-b.second)>0;
}

void dodaj(pair < ll, ll > p){
//	cout << "dodaj" << endl;
//	cout << p.first << " " << p.second << '\n';
	while(ljusk.size()>1 && !ccw(p, ljusk.back(), ljusk[ljusk.size()-2])){
//		cout << "brisi" << endl;
//		cout << ljusk.back().first << " " << ljusk.back().second << endl;
		ljusk.pop_back();
	}
	ljusk.push_back(p);
}

ll query(ll x, ll y){
	int lo=0, hi=ljusk.size()-1, mid;
	while(lo<hi){
		mid=(lo+hi)/2;
		if(ljusk[mid].first*x+ljusk[mid].second*y<ljusk[mid+1].first*x+ljusk[mid+1].second*y){
			hi=mid;
		}
		else{
			lo=mid+1;
		}
	}
/*	for(int i=0; i<ljusk.size(); i++){
		cout << ljusk[i].first*x+ljusk[i].second*y << " ";
	}
	cout << '\n';*/
	return ljusk[lo].first*x+ljusk[lo].second*y;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin >> n;
	pair < int, int > p;
	for(int i=0; i<n; i++){
		cin >> p.first >> p.second;
		p.first=abs(p.first);
		p.second=abs(p.second);
		if(!bio[p]){
			bio[p]=1;
			v.push_back(p);
		}
	}
	n=v.size();
	sort(v.begin(), v.end());
	for(int i=0; i<n; i++){
		while(!q.empty() && q.back().second<=v[i].second){
			q.pop_back();
		}
		q.push_back(v[i]);
	}
	v.clear();
	while(!q.empty()){
		v.push_back(q.front());
		q.pop_front();
	}
	n=v.size();
/*	cout << "A niz je" << endl;
	for(int i=0; i<n; i++){
		cout << v[i].first << " " << v[i].second << '\n';
	}
	cout << "................" << endl;*/
	dodaj({v[0].second, 0});
	for(int i=0; i<n; i++){
		dp[i]=query(v[i].first, 1);
		if(i<n-1){
			dodaj({v[i+1].second, dp[i]});
		}
	}
/*	for(int i=0; i<n; i++){
		cout << dp[i] << " ";
	}
	cout << '\n';*/
	cout << dp[n-1]*4 << '\n';
	return 0;
}

• Subtask 1: 120 / 120