POJ 1456 Supermarket

Supermarket

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 6961		Accepted: 2903

Description

A supermarket has a set Prod of products on sale. It earns a profit px for each product x∈Prod sold by a deadline dx that is measured as an integral number of time units starting from the moment the sale begins. Each product takes precisely one unit of time for being sold. A selling schedule is an ordered subset of products Sell ≤ Prod such that the selling of each product x∈Sell, according to the ordering of Sell, completes before the deadline dx or just when dx expires. The profit of the selling schedule is Profit(Sell)=Σx∈Sellpx. An optimal selling schedule is a schedule with a maximum profit.
For example, consider the products Prod={a,b,c,d} with
(pa,da)=(50,2), (pb,db)=(10,1), (pc,dc)=(20,2), and (pd,dd)=(30,1). The
possible selling schedules are listed in table 1. For instance, the
schedule Sell={d,a} shows that the selling of product d starts at time 0
and ends at time 1, while the selling of product a starts at time 1 and
ends at time 2. Each of these products is sold by its deadline. Sell is
the optimal schedule and its profit is 80.



Write a program that reads sets of products from an input text file
and computes the profit of an optimal selling schedule for each set of
products.

Input

A set
of products starts with an integer 0 <= n <= 10000, which is the
number of products in the set, and continues with n pairs pi di of
integers, 1 <= pi <= 10000 and 1 <= di <= 10000, that
designate the profit and the selling deadline of the i-th product. White
spaces can occur freely in input. Input data terminate with an end of
file and are guaranteed correct.
Output

For
each set of products, the program prints on the standard output the
profit of an optimal selling schedule for the set. Each result is
printed from the beginning of a separate line.
Sample Input

4  50 2  10 1   20 2   30 1

7  20 1   2 1   10 3  100 2   8 2
5 20  50 10

Sample Output

80
185

Hint

The sample input contains two product sets. The first set encodes the products from table 1. The second set is for 7 products. The profit of an optimal schedule for these products is 185.
Source

Southeastern Europe 2003
//开始以为只有一组测试数据呢
//贪心，然赚钱多的尽可能被卖掉

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
#include <cmath>
#define N 10002
using namespace std;
struct node
{
int val,last;
bool operator<(const node&a)const
{
return val>a.val;
}
};
node gy
;
bool h
;
int main()
{
int n,sum;
int i,k;
while(scanf("%d",&n)!=EOF)
{
sum=0;
memset(h,0,sizeof(h));
for(i=0;i<n;i++)
scanf("%d%d",&gy[i].val,&gy[i].last);
sort(gy,gy+n);
for(i=0;i<n;i++)
for(k=gy[i].last;k>0;k--)
if(!h[k])
{
sum+=gy[i].val;
h[k]=1;
break;
}
printf("%d\n",sum);
}
return 0;
}