Cod sursă (job #672333)

// #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;
long long bestTime;
int state;
 
void initProcess();
void status_1();
void status_2();
long long simulate_finish();
void status_5();
 
void initProcess(){
  currentTime = minerals = 0;
  currentSCV = 1;
  state = 1;
  bestTime = L;
}
 
void status_1() {
  if (currentTime > L) {
    state = 6;
  }
  bestTime = min(bestTime, simulate_finish());
  state = 2;
}
 
void status_2() {
  if (costNewSCV <= minerals) {
    minerals -= costNewSCV;
    state = 5;
    return;
  }

  long long deltaTime = (costNewSCV - minerals + currentSCV * productionSCV - 1)
                        / (currentSCV * productionSCV);
  currentTime += deltaTime;
  minerals += deltaTime * currentSCV * productionSCV;
  if (currentTime > L) {
    state = 6;
  } else {
    minerals -= costNewSCV;
    state = 5;
  }
}
 
long long simulate_finish() {
  if (goalProduction <= minerals) {
    return currentTime;
  }

  long long deltaTime = (goalProduction - minerals + currentSCV * productionSCV - 1)
                        / (currentSCV * productionSCV);
  if (currentTime + deltaTime > L) {
    return L;
  } else {
    return currentTime + deltaTime;
  }
}
 
void status_5() {
  minerals += currentSCV * productionSCV * timeNewSCV;
  currentTime += timeNewSCV;
  if (currentTime > L) {
    state = 6;
  } else {
    currentSCV++;
    state = 1;
  }
}
 
int main(){
  fin >> costNewSCV >> timeNewSCV >> productionSCV >> goalProduction;
  initProcess();
  int iter = L;
  while (currentTime < bestTime && state != 6 && iter) {
    // cerr << state << " " << currentTime << " " << bestTime << endl;
    switch (state) {
      case 1:
        status_1();
        break;
      case 2:
        status_2();
        break;
      case 5:
        status_5();
        break;
    }
    iter--;
  }

  fout << bestTime << "\n";
  return 0;
}