#include<bits/stdc++.h>
#include "railroad.h"
using namespace std;
using ll=long long;
const ll MAX_TRANSFO=4*200*1000+5,INFINI=(ll)1000*1000*1000*1000*1000*1000;
ll nbTransfo,rep,nbInter;
ll seuil[MAX_TRANSFO],valNouv[MAX_TRANSFO],vraiVal[MAX_TRANSFO];
set<ll> listeInter;
ll valInter[MAX_TRANSFO];
unordered_map<ll,ll> transfo;
ll cumu[MAX_TRANSFO];
ll pere[MAX_TRANSFO];
ll find(ll pos) {
if (pere[pos]!=pos) {
pere[pos]=find(pere[pos]);
}
return pere[pos];
}
ll unir(ll deb,ll fin) {
if (find(deb)!=find(fin)) {
pere[find(deb)]=find(fin);
return 1;
}
return 0;
}
ll plan_roller_coaster(vector<int> s,vector<int> t) {
nbTransfo=s.size();
for (ll i=0;i<nbTransfo;i++) {
seuil[i]=s[i];
listeInter.insert(seuil[i]);
valNouv[i]=t[i];
listeInter.insert(valNouv[i]);
}
seuil[nbTransfo]=INFINI;
listeInter.insert(INFINI);
valNouv[nbTransfo]=1;
listeInter.insert(1);
nbTransfo++;
for (ll i:listeInter) {
vraiVal[nbInter]=i;
transfo[i]=nbInter;
nbInter++;
}
for (ll i=0;i<nbInter;i++) {
pere[i]=i;
}
for (ll i=0;i<nbTransfo;i++) {
cumu[transfo[seuil[i]]]++;
cumu[transfo[valNouv[i]]]--;
unir(transfo[seuil[i]],transfo[valNouv[i]]);
}
vector<pair<ll,ll>> distTri;
for (ll i=0;i<nbInter-1;i++) {
cumu[i+1]+=cumu[i];
rep+=(vraiVal[i+1]-vraiVal[i])*(max(cumu[i],(ll)0));
if (cumu[i]!=0) {
unir(i+1,i);
}
distTri.push_back({vraiVal[i+1]-vraiVal[i],i});
}
sort(distTri.begin(),distTri.end());
for (auto i:distTri) {
if (unir(i.second,i.second+1)==1) {
rep+=i.first;
}
}
return rep;
}
