BZOJ 1634: [Usaco2007 Jan]Protecting the Flowers

题目链接：http://www.lydsy.com/JudgeOnline/problem.php?id=1634

解：大力贪心。。。

每次取d/t最大的那个。

程序：

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
struct ding{
  int t,d;
  double y;
}x[200000];
int n;
bool cmp(const ding&a,const ding&b){return (a.y>b.y);}
int main()
{
  scanf("%d",&n);
  for (int i=1;i<=n;i++) 
  {
    scanf("%d%d",&x[i].t,&x[i].d);
    x[i].y=(double)x[i].d/x[i].t;
  }
  sort(x+1,x+1+n,cmp);
  long long ans=0,tim=0;
  for (int i=1;i<=n;i++)
  {
      ans+=tim*x[i].d;
      tim+=x[i].t+x[i].t;
  }
  printf("%lld\n",ans);
  return 0;
}