Cod sursă (job #672328)

// #include <bits/stdc++.h>
#include <fstream>
// #include <iostream>
#define L 5e6 + 5
#define FAIL L + 1

// #define fin cin
// #define fout cout

using namespace std;

ifstream fin("scv.in");
ofstream fout("scv.out");
 
long long costNewSCV, timeNewSCV, productionSCV, goalProduction;
long long currentTime, currentSCV, minerals, totalSCV;
bool success;
 
inline void startProcess(long long numberOfSCV);
inline void status_1();
inline void status_2();
inline void status_3();
inline void status_4();
inline void status_5();
inline void status_6();
 
inline void startProcess(long long numberOfSCV){
  totalSCV = numberOfSCV;
  currentTime = minerals = 0;
  currentSCV = 1;
  ///cout << "PROCESS STARTED!\n";
  status_1();
  if (!success)
    currentTime = FAIL;
}
 
inline void status_1(){
  ///cout << "STATUS_1 was triggered!\n";
  ///cout << "CURRENT_TIME = " << currentTime << "\n";
  /**
  if (currentTime > 2e5){
    cout << "CURRENT_SCV = " << currentSCV << "\n";
    cout << "MINERALS = " << minerals << "\n";
  }
  **/
  if (currentSCV < totalSCV)
    status_2();
  else
    status_3();
}
 
inline void status_2(){
  ///cout << "STATUS_2 was triggered!\n";
  if (costNewSCV <= minerals) {
    minerals -= costNewSCV;
    status_5();
    return;
  }

  int deltaTime = (costNewSCV - minerals + currentSCV * productionSCV - 1) / (currentSCV * productionSCV);
  currentTime += deltaTime;
  minerals += deltaTime * currentSCV * productionSCV;
  if (currentTime > L)
    status_6();
  else {
    minerals -= costNewSCV;
    status_5();
  }
 
 
  /*
  if (currentTime > L){
    ///cout << "STATUS_2 triggered FAIL!\n";
    status_6();
  }
  else if (minerals < costNewSCV){
    minerals = minerals + currentSCV * productionSCV;
    currentTime++;
    status_2();
  }
  else{
    minerals -= costNewSCV;
    status_5();
  }
  */
}
 
inline void status_3(){
  ///cout << "STATUS_3 was triggered!\n";
  if (goalProduction <= minerals) {
    status_4();
    return;
  }

  int deltaTime = (goalProduction - minerals + currentSCV * productionSCV - 1) / (currentSCV * productionSCV);
  currentTime += deltaTime;
  minerals += deltaTime * currentSCV * productionSCV;
  if (currentTime > L)
    status_6();
  else
    status_4();
 
 
 
  /*
  if (currentTime > L){
    ///cout << "STATUS_3 triggered FAIL!\n";
    status_6();
  }
  else if (minerals < goalProduction){
    minerals = minerals + currentSCV * productionSCV;
    currentTime++;
    status_3();
  }
  else
    status_4();
  */
}
 
inline void status_4(){
  ///cout << "SUCCESS!\n";
  success = true;
}
 
inline void status_5(){
  //long long i;
  //bool failed = false;
  ///cout << "STATUS_5 was triggered!\n";
  minerals += currentSCV * productionSCV * timeNewSCV;
  currentTime += timeNewSCV;
  if (currentTime > L)
    status_6();
  else{
    currentSCV++;
    status_1();
  }
 
 
 
 
  /*
  for (i = 0; i < timeNewSCV; i++){
    if (currentTime > L){
      i = timeNewSCV;
      failed = true;
    }
    minerals = minerals + currentSCV * productionSCV;
    currentTime++;
  }
  if (failed){
    ///cout << "STATUS_5 triggered FAIL!\n";
    status_6();
  }
  else{
    currentSCV++;
    status_1();
  }
  */
}
 
inline void status_6(){
  ///cout << "FAIL!\n";
  success = false;
}
 
int main(){
  long long le, ri, mid1, mid2, best, time1, time2;
  fin >> costNewSCV >> timeNewSCV >> productionSCV >> goalProduction;
  /**
  startProcess(3);
  cout << currentTime << "\n";
  **/
  /**/
  le = best = 1;
  ///ri = L;
  ri = goalProduction + 1;
  while (le <= ri){
    mid1 = le + (ri - le) / 3;
    mid2 = le + 2 * (ri - le) / 3;
 
    ///cout << "Process was started for " << mid1 << ".\n";
    startProcess(mid1);
    time1 = currentTime;
    ///cout << "CurrentTime is " << time1 << ".\n\n";
 
    ///cout << "Process was started for " << mid2 << ".\n";
    startProcess(mid2);
    time2 = currentTime;
    ///cout << "CurrentTime is " << time2 << ".\n\n";
 
    if (time1 < time2){
      best = time1;
      ri = mid2 - 1;
    }
    else{
      best = time2;
      le = mid1 + 1;
    }
  }
  fout << best << "\n";
  /**/
  return 0;
}