#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include "railroad.h"
using namespace std;
// <|°_°|>
const int INFINI = (1000 * 1000 * 1000);
const int MAX_COORD = (400 * 1000 + 2);
int Dsu[MAX_COORD];
pair <int, int> Evenements[MAX_COORD];
int Sommes[MAX_COORD];
int Correspondances[MAX_COORD];
pair <int, int> Aretes[MAX_COORD];
int nbAretes = 0;
long long coutTotal = 0;
int nbSections;
int Find(int a) {
if (Dsu[a] < 0)
return a;
return Dsu[a] = Find(Dsu[a]);
}
void Union(int a, int b) {
int rA = Find(a), rB = Find(b);
if (rA == rB)
return;
if (Dsu[rA] > Dsu[rB])
swap(rA, rB);
Dsu[rA] += Dsu[rB];
Dsu[rB] = rA;
return;
}
long long plan_roller_coaster(vector<int> Entrees, vector<int> Sorties) {
Entrees.push_back(INFINI);
Sorties.push_back(1);
nbSections = Entrees.size();
for (int i = 0; i < nbSections; i ++)
{
Evenements[2 * i] = {Entrees[i], i + 1};
Evenements[2 * i + 1] = {Sorties[i], - (i + 1)};
}
sort(Evenements, Evenements + 2 * nbSections);
int nbDiff = 0;
for (int i = 0; i < 2 * nbSections; i ++)
{
int dep = i;
while (i < 2 * nbSections && Evenements[i].first == Evenements[i + 1].first)
i ++;
for (int j = dep; j <= i; j ++)
{
int id = Evenements[j].second;
if (id > 0)
{
Entrees[id - 1] = nbDiff;
Sommes[nbDiff] ++;
}
else
{
Sorties[- id - 1] = nbDiff;
Sommes[nbDiff] --;
}
}
Correspondances[nbDiff ++] = Evenements[i].first;
}
for (int i = 0; i < nbDiff; i ++)
{
Dsu[i] = -1;
}
for (int i = 0; i < nbSections; i ++)
{
Union(Entrees[i], Sorties[i]);
}
int nbOuverts = 0;
for (int i = 0; i < nbDiff - 1; i ++)
{
nbOuverts += Sommes[i];
coutTotal += max(0, nbOuverts) * (Correspondances[i + 1] - Correspondances[i]);
if (nbOuverts != 0)
{
Union(i, i + 1);
}
else if (Find(i) != Find(i + 1))
{
Aretes[nbAretes ++] = {Correspondances[i + 1] - Correspondances[i], i};
}
}
sort(Aretes, Aretes + nbAretes);
for (int i = 0; i < nbAretes; i ++)
{
int id = Aretes[i].second;
if (Find(id) != Find(id + 1))
{
coutTotal += Correspondances[id + 1] - Correspondances[id];
Union(id, id + 1);
}
}
return coutTotal;
}
