NYOJ 248

清疚 2022-06-17 10:28 104阅读 0赞

## BUYING FEED ##

时间限制： 3000 ms  |  内存限制： 65535 KB

难度： 4

描述

Farmer** John** needs to travel to town to pick up K (1 <= K <= 100)pounds of feed. Driving D miles with K pounds of feed in his truck costs **D\*K** cents.

The county feed lot has N (1 <= N<= 100) stores (conveniently numbered 1..N) that sell feed. Each store is located on a segment of the X axis whose length is E (1 <= E <= 350). Store i is at location X\_i (0 < X\_i < E) on the number line and can sell **John** as much as F\_i (1 <= F\_i <= 100) pounds of feed at a cost of C\_i (1 <= C\_i <= 1,000,000) cents per pound.  
Amazingly, a given point on  the X axis might have more than one store.

Farmer** John ** starts  at location 0 on this number line and can drive only in the positive direction, ultimately arriving at location E, with at least **K** pounds of feed. He can stop at any of the feed stores along the way and buy any amount of feed up to the the store's limit.  What is the minimum amount Farmer **John** has to pay to buy and transport the K pounds of feed? Farmer** John**  
knows there is a solution. Consider a sample where Farmer** John  **needs two pounds of feed from three stores (locations: 1, 3, and 4) on a number line whose range is 0..5:       
0   1   2  3   4   5      
\---------------------------------           
1       1   1                Available pounds of feed           
1       2   2               Cents per pound

It is best for **John** to buy one pound of feed from both the second and third stores. He must pay two cents to buy each pound of feed for a total cost of 4. When** John** travels from 3 to 4 he is moving 1 unit of length and he has 1 pound of feed so he must pay1\*1 = 1 cents.

When **John** travels from 4 to 5 heis moving one unit and he has 2 pounds of feed so he must pay 1\*2 = 2 cents. The total cost is 4+1+2 = 7 cents.

输入

The first line of input contains a number c giving the number of cases that follow  
There are multi test cases ending with EOF.  
Each case starts with a line containing three space-separated integers: K, E, and N  
Then N lines follow :every line contains three space-separated integers: Xi Fi Ci

输出

For each case,Output A single integer that is the minimum cost for FJ to buy and transport the feed

样例输入

2 5 3

3 1 2

4 1 2

1 1 1

样例输出

一条数轴上有n个商店，第i个商店在Xi的位置，最多可以卖Fi磅feed，每磅Ci元。一个人从起点0开始，终点为E，当他到达E点时，至少要买K磅feed，带着1磅feed每前进一个单位，就要额外花费1元。求最小花费是多少。

第一行输入一个数C数据的组数；

第二行输入三个数K E N；

接下来的N行，每一行包含三个整数Xi Fi Ci；

输出：对于每一个例子输出一个整数，表示John需要花费的最小的钱数；

大致思想：求出每个商店（每一点）每买一磅食物需要的价钱，价钱中包括从这点运到终点需要的运费

#include<bits/stdc++.h>
    using namespace std;
    struct node
    {
        int pay;
        int get;
    }w[1001];
    bool cmp(node x,node y)
    {
        if(x.pay<y.pay) return true;
        return false;
    }
    int main()
    {
        int t;
        scanf("%d",&t);
        while(t--)
        {
            int k,e,n,num,prize,sum;
            scanf("%d%d%d",&k,&e,&n);
            for(int i=0;i<n;i++)
            {
                scanf("%d%d%d",&num,&w[i].get,&prize);
            w[i].pay=(e-num)+prize;
            }
            sort(w,w+n,cmp);
            sum=0;
            for(int i=0;i<n;i++)
            {
                if(w[i].get>=k)
                {
                    sum=sum+k*w[i].pay;
                    break;
                }
                else
                {
                    sum=sum+w[i].pay*w[i].get;
                    k=k-w[i].get;
                }
            }
            printf("%d\n",sum);
        }
        return 0;
    }