（并查集 贪心思想）Supermarket -- POJ --1456

#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<cstdlib>

using namespace std;

#define N 11000
#define INF 0xfffffff

struct node
{
    int a,b;

}p[N];

int cmp(node a, node b)
{
	return a.a > b.a;
}
int main()
{
    int n,i,j,vis[N];
    while(scanf("%d",&n)!=EOF)
    {
        memset(vis,0,sizeof(vis));
        memset(p,0,sizeof(p));

        for(i=0;i<n;i++)
        scanf("%d %d",&p[i].a,&p[i].b);

        sort(p,p+n,cmp);

        int sum=0;
        for(i=0;i<n;i++)
        {
            for(j=p[i].b;j>0;j--)
            {
                if(vis[j]==0)
                {
                    sum=sum+p[i].a;
                    vis[j]=1;
                    break;
                }
            }
        }
        printf("%d
",sum);
    }
    return 0;
}