1070 Mooncake (25 分)

Mooncake is a Chinese bakery product traditionally eaten during the Mid-Autumn Festival. Many types of fillings and crusts can be found in traditional mooncakes according to the region's culture. Now given the inventory amounts and the prices of all kinds of the mooncakes, together with the maximum total demand of the market, you are supposed to tell the maximum profit that can be made.

Note: partial inventory storage can be taken. The sample shows the following situation: given three kinds of mooncakes with inventory amounts being 180, 150, and 100 thousand tons, and the prices being 7.5, 7.2, and 4.5 billion yuans. If the market demand can be at most 200 thousand tons, the best we can do is to sell 150 thousand tons of the second kind of mooncake, and 50 thousand tons of the third kind. Hence the total profit is 7.2 + 4.5/2 = 9.45 (billion yuans).

Input Specification:

Each input file contains one test case. For each case, the first line contains 2 positive integers N (≤1000), the number of different kinds of mooncakes, and D (≤500 thousand tons), the maximum total demand of the market. Then the second line gives the positive inventory amounts (in thousand tons), and the third line gives the positive prices (in billion yuans) of N kinds of mooncakes. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print the maximum profit (in billion yuans) in one line, accurate up to 2 decimal places.

Sample Input:

3 200
180 150 100
7.5 7.2 4.5

Sample Output:

9.45

 

题⽬⼤意：N表示⽉饼种类，D表示⽉饼的市场最⼤需求量，给出每种⽉饼的数量和总价，问根据市场

最⼤需求量，这些⽉饼的最⼤销售利润为多少～

分析：⾸先根据⽉饼的总价和数量计算出每⼀种⽉饼的单价，然后将⽉饼数组按照单价从⼤到⼩排

序，根据需求量need的⼤⼩，从单价最⼤的⽉饼开始售卖，将销售掉这种⽉饼的价格累加到result中，

最后输出result即可～

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
struct mooncake{
float mount, price, unit;
};
int cmp(mooncake a, mooncake b) {
    return a.unit > b.unit; 
}
int main() {
    int n, need;
    cin >> n >> need;
    vector<mooncake> a(n);
    for ( int i = 0; i < n; i++) 
	      scanf("%f", &a[i].mount);
    for ( int i = 0; i < n; i++) 
	      scanf("%f", &a[i].price);
    for ( int i = 0; i < n; i++) 
	      a[i].unit = a[i].price / a[i].mount;
    sort(a.begin(), a.end(), cmp);
    float result = 0.0;
    for ( int i = 0; i < n; i++) {
    if ( a[i].mount <= need) {
         result = result + a[i].price;
    } else {
         result = result + a[i].unit * need;
         break;
    }
    need = need - a[i].mount;
    }
    printf("%.2f",result);
    return 0; 
}