1033.To Fill or Not to Fill (25)

1033.To Fill or Not to Fill (25)

pat-al-1033

2017-02-05

• 贪心
• 在起始处没有加油站所以一步也走不了的情况特殊处理一下
• 分三种情况，一是油箱加满也到不了下一个加油站（直接print能到的最远处然后return 0）、二是能走到的距离内有比当前站油价低的（就加够可以行驶到那一站的油就可以了）、三是能走到的距离内有加油站但没有比当前油价低的（那就加满油，行驶到油价最低的站点）
• 注意：油箱内剩余油量的更新

/** * pat-al-1033 * 2017-02-05 * Cpp version * Author: fengLian_s */#include<stdio.h>#include<vector>#include<algorithm>#define INF 0x3f3f3f3fusing namespace std;struct STA{  double price;  double dist;};bool cmp(STA a, STA b){  return a.dist < b.dist;}int main(){  freopen("in.txt", "r", stdin);  int maxC, maxDist, avgDis, n;  scanf("%d%d%d%d", &maxC, &maxDist, &avgDis, &n);  vector<STA> sta(n+1);  sta[0].price = 0;  sta[0].dist = maxDist;  for(int i = 1;i <= n;i++)  {    scanf("%lf%lf", &sta[i].price, &sta[i].dist);  }  sort(sta.begin(), sta.end(), cmp);  double tmpDist = 0, maxCanReach = 0, tmpPrice = 0, totalPrice = 0, tmpC = 0;//tmpC是目前油箱里的油量  if(sta[0].dist != 0)  {    printf("The maximum travel distance = 0.00\n");    return 0;  }  else    tmpPrice = sta[0].price;  while(tmpDist < maxDist)  {    maxCanReach = tmpDist + maxC * avgDis;    double minPrice = INF, minPriceDist;    int flagFind = 0;    for(int i = 1;i <= n && sta[i].dist <= maxCanReach;i++)    {      if(sta[i].dist <= tmpDist)        continue;      if(sta[i].price < tmpPrice)      {        //printf("sta.price = %.2lf, tmpPrice = %.2lf\n", sta[i].price, tmpPrice);        totalPrice += ((sta[i].dist - tmpDist) / avgDis - tmpC) * tmpPrice;        //printf("falgFind, totalPrice = %.2lf, tmpDist = %d\n", totalPrice, (int)tmpDist);        tmpC = 0;        tmpPrice = sta[i].price;        tmpDist = sta[i].dist;        flagFind = 1;        break;      }      if(sta[i].price < minPrice)      {        minPrice = sta[i].price;        minPriceDist = sta[i].dist;        //printf("minPriceDist = %d, minPrice = %.2lf\n", (int)minPriceDist, minPrice);      }    }    if(flagFind == 0 && minPrice == INF)    {      printf("The maximum travel distance = %.2lf\n", maxCanReach);      return 0;    }    if(flagFind == 0 && minPrice != INF)    {      totalPrice += (maxC - tmpC) * tmpPrice;      tmpC = maxC - (minPriceDist - tmpDist) / avgDis;      //printf("totalPrice = %.2lf, tmpDist = %d\n", totalPrice, (int)tmpDist);      tmpPrice = minPrice;      tmpDist = minPriceDist;      //printf("minPriceDist = %d, minPrice = %.2lf\n", (int)minPriceDist, minPrice);    }  }  printf("%.2lf\n", totalPrice);  return 0;}

-FIN-