7-32 To Fill or Not to Fill

题目

题意： 给定油站的位置以及价格，要求要在汽车油量为零的情况下加到最便宜的油到达目的地

tip：贪心

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
const int inf = 99999999;
struct station {
	double price, dis;
	bool operator < (const struct station a)const{
	return dis<a.dis;
	}
};
int main() {
	double cmax, d, davg;
	int n;
	scanf("%lf%lf%lf%d", &cmax, &d, &davg, &n);
	vector<station> sta(n + 1);
	sta[0] = {0.0, d};
	for(int i = 1; i <= n; i++)
		cin>>sta[i].price>>sta[i].dis;
	sort(sta.begin(), sta.end());
	double nowdis = 0.0, maxdis = 0.0, nowprice = 0.0, totalPrice = 0.0, leftdis = 0.0;
	if(sta[0].dis != 0) {
		printf("The maximum travel distance = 0.00");
		return 0;
	} else 
		nowprice = sta[0].price;
	while(nowdis < d) {
		maxdis = nowdis + cmax * davg;
		double minPriceDis = 0, minPrice = inf;
		int flag = 0;
		for(int i = 1; i <= n && sta[i].dis <= maxdis; i++) {
			if(sta[i].dis <= nowdis) continue;
			if(sta[i].price < nowprice) {
				totalPrice += (sta[i].dis - nowdis - leftdis) * nowprice / davg;
				leftdis = 0.0;
				nowprice = sta[i].price;
				nowdis = sta[i].dis;
				flag = 1;
				break;
			}
			if(sta[i].price < minPrice) {
				minPrice = sta[i].price;
				minPriceDis = sta[i].dis;
			}
		}
		if(flag == 0 && minPrice != inf) {
			totalPrice += (nowprice * (cmax - leftdis / davg));
			leftdis = cmax * davg - (minPriceDis - nowdis);
			nowprice = minPrice;
			nowdis = minPriceDis;
		}
		if(flag == 0 && minPrice == inf) {
			nowdis += cmax * davg;
			printf("The maximum travel distance = %.2lf", nowdis);
			return 0;
		}
	}
	printf("%.2lf", totalPrice);
	return 0;
}