Submission #63110

#	Time	Username	Problem	Language	Result	Execution time	Memory
63110		Arturgo	Arranging Tickets (JOI17_arranging_tickets)	C++11	100 / 100	2726 ms	49220 KiB

arranging_tickets

#include <iostream>
#include <vector>
#include <queue>
#include <cstdio>
using namespace std;

const long long INFINI = 1000ll * 1000ll * 1000ll * 1000ll * 1000ll;

struct Inter {
  int deb, fin, num;
  Inter(int _deb = 0, int _fin = 0, int _num = 0) {
    deb = _deb;
    fin = _fin;
    num = _num;
  }
};

bool operator < (const Inter &a, const Inter &b) {
  return a.fin < b.fin;
}

int nbStations, nbReqs;
long long hauteurs[300*1000];
vector<Inter> inters[300*1000];

bool check(long long maxi, int pos, long long nbInvs) {
  vector<long long> invs(nbStations, 0);

  priority_queue<Inter> ouverts;
  
  long long nbOuverts = 0;
  
  for(int iStation = 0;iStation <= pos;iStation++) {
    for(Inter inter : inters[iStation]) {
      if(inter.fin > pos) {
	ouverts.push(inter);
      }
    }
    
    long long besoin = (hauteurs[iStation] + nbInvs - maxi + 1) / 2;
    if(iStation == pos) {
      besoin = nbInvs;
    }

    long long doitOuvrir = max(0ll, besoin - nbOuverts);
    nbOuverts += doitOuvrir;
    
    while(doitOuvrir > 0) {
      if(ouverts.empty())
	return false;
      Inter mel = ouverts.top();
      ouverts.pop();

      long long nbPose = min<long long>(mel.num, doitOuvrir);

      invs[0] += nbPose;
      invs[mel.deb] -= 2 * nbPose;
      invs[mel.fin] += 2 * nbPose;

      mel.num -= nbPose;
      doitOuvrir -= nbPose;

      if(mel.num != 0) {
	ouverts.push(mel);
      }
    }
  }

  if(hauteurs[0] + invs[0] > maxi)
    return false;
  
  for(int iStation = 1;iStation < nbStations;iStation++) {
    invs[iStation] += invs[iStation - 1];
    if(hauteurs[iStation] + invs[iStation] > maxi)
      return false;
  }
  return true;
}

bool estPossible(long long maxTickets) {
  int maxGauche = 0;
  int maxDroite = 0;

  for(int iStation = 0;iStation < nbStations;iStation++) {
    if(hauteurs[iStation] > hauteurs[maxGauche]) {
      maxGauche = iStation;
    }
    if(hauteurs[iStation] >= hauteurs[maxDroite]) {
      maxDroite = iStation;
    }
  }

  if(hauteurs[maxGauche] <= maxTickets)
    return true;

  return check(maxTickets, maxGauche, hauteurs[maxGauche] - maxTickets) ||
    check(maxTickets, maxGauche, hauteurs[maxGauche] - maxTickets + 1) ||
    check(maxTickets, maxDroite, hauteurs[maxDroite] - maxTickets) ||
    check(maxTickets, maxDroite, hauteurs[maxDroite] - maxTickets + 1);
}

int main() {
  scanf("%d%d", &nbStations, &nbReqs);

  for(int iReq = 0;iReq < nbReqs;iReq++) {
    int deb, fin, num;
    scanf("%d%d%d", &deb, &fin, &num);

    if(fin < deb)
      swap(deb, fin);
    
    deb--; fin--;
    hauteurs[deb] += num;
    hauteurs[fin] -= num;
    inters[deb].push_back(Inter(deb, fin, num));
    inters[fin].push_back(Inter(deb, fin, num));
  }

  for(int iStation = 1;iStation < nbStations;iStation++) {
    hauteurs[iStation] += hauteurs[iStation - 1];
  }

  long long deb = 0, fin = INFINI;

  while(fin - deb > 1) {
    long long mil = (deb + fin) / 2;
    if(estPossible(mil)) {
      fin = mil;
    }
    else {
      deb = mil;
    }
  }

  printf("%lld\n", deb + 1);
  
  return 0;
}

Compilation message (stderr)

arranging_tickets.cpp: In function 'int main()':
arranging_tickets.cpp:103:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &nbStations, &nbReqs);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arranging_tickets.cpp:107:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d", &deb, &fin, &num);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 35 / 35
• Subtask 3: 20 / 20
• Subtask 4: 20 / 20
• Subtask 5: 15 / 15