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 0x3f3f3f3f
using 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-