zoukankan      html  css  js  c++  java
  • PAT 1070. Mooncake (25)

    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
    
    此题没有什么难度,就是一个贪心算法,或者说是一个分数背包问题,唯一需要注意的是题目中不能讲amounts的类型设为int,要设为double,不然有一个测试点过不了的,PAT就是一个坑啊。
    #include <vector>
    #include <algorithm>
    #include <cstdio>
    #include <functional>
    using namespace std;
    
    const int NUM=1001;
    
    struct Mooncake
    {
        double amounts;
        double prices;
        double rate;
        Mooncake()
        {
            amounts=0.0;
            prices=0.0;
            rate=0.0;
        }
    };
    
    class Greater:public binary_function<Mooncake,Mooncake,bool>
    {
    public:
        bool operator()(const Mooncake& lhs,const Mooncake& rhs) const
        {
            return lhs.rate>rhs.rate;
        }
    };
    
    vector<Mooncake> mooncakes;
    int main()
    {
        int N,D;
        double amounts,prices;
        Mooncake buf;
        scanf("%d%d",&N,&D);
        int i=0;
        for(;i<N;++i)
        {
            scanf("%lf",&amounts);
            buf.amounts=amounts;
            mooncakes.push_back(buf);
        }
        for(i=0;i<N;++i)
        {
            scanf("%lf",&prices);
            mooncakes[i].prices=prices;
            mooncakes[i].rate=mooncakes[i].prices/(double)mooncakes[i].amounts;
        }
        sort(mooncakes.begin(),mooncakes.end(),Greater());
        double maxProfit=0.0;
        for(i=0;i<N&&D>0;++i)
        {
            if(D>=mooncakes[i].amounts)
            {
                maxProfit+=mooncakes[i].prices;
                D-=mooncakes[i].amounts;
            }
            else
            {
                maxProfit+=mooncakes[i].rate*D;
                D=0;
            }
        }
        printf("%.2f
    ",maxProfit);
        return 0;
    }
    View Code
  • 相关阅读:
    应当将指针变量用“==”或“!=”与 NULL 比较
    不可将浮点变量用“==”或“!=”与任何数字比较
    应当将整型变量用“==”或“!=”直接与 0 比较
    不可将布尔变量直接与 TRUE、FALSE 或者 1、0 进行比较
    不要把程序中的复合表达式与“真正的数学表达式”混淆
    不要有多用途的复合表达式
    不要编写太复杂的复合表达式
    用括号确定表达式的操作顺序
    为了防止某一软件库中的一些标识符和其它软件库中的冲突
    类的数据成员加前缀 m_(表示 member)
  • 原文地址:https://www.cnblogs.com/wwblog/p/3704675.html
Copyright © 2011-2022 走看看