试题描述: 约翰留下他的N(N<=100000)只奶牛上山采木．他离开的时候,她们像往常一样悠闲地在草场里吃草．可是,当他回来的时候,他看到了一幕惨剧:牛们正躲在他的花园里,啃食着他心爱的美丽花朵!为了使接下来花朵的损失最小,约翰赶紧采取行动,把牛们送回牛棚． 牛们从1到N编号．第i只牛所在的位置距离牛棚Ti(1≤Ti≤2000000)分钟的路程,而在约翰开始送她回牛棚之前,她每分钟会啃食Di(1≤Di≤100)朵鲜花．无论多么努力,约翰一次只能送一只牛回棚．而运送第第i只牛事实上需要2Ti分钟…

Protecting the Flowers 护花 bzoj-1634 Usaco-2007 Jan 题目大意:n头牛,每头牛有两个参数t和atk.表示弄走这头牛需要2*t秒,这头牛每秒会啃食atk朵花.求一个弄走牛的顺序,使得这些牛破坏最少的花. 注释:$1\le n \le 10^5$. 想法:贪心. 两头牛i和j. 只考虑这两头牛的位置. 如果i在j前面,拉走i的时候j会造成$2t_i*atk_j$朵花.反之同理. 比较两者谁大就放在前面. 在cmp中这样写就行了. 最后,附上丑陋的代码.…

1634: [Usaco2007 Jan]Protecting the Flowers 护花 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 448  Solved: 276[Submit][Status] Description Farmer John went to cut some wood and left N (2 <= N <= 100,000) cows eating the grass, as usual. When he retur…

1634: [Usaco2007 Jan]Protecting the Flowers 护花 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 885  Solved: 575[Submit][Status][Discuss] Description Farmer John went to cut some wood and left N (2 <= N <= 100,000) cows eating the grass, as usual. When…

题目描述 Farmer John went to cut some wood and left N (2 <= N <= 100,000) cows eating the grass, as usual. When he returned, he found to his horror that the cows were in his garden eating his beautiful flowers. Wanting to minimize the subsequent damage,…

考虑相邻的两头奶牛 a , b , 我们发现它们顺序交换并不会影响到其他的 , 所以我们可以直接按照这个进行排序 --------------------------------------------------------------------------------- #include<cstdio> #include<cstring> #include<algorithm> #include<iostream>   #define rep( i ,…

1634: [Usaco2007 Jan]Protecting the Flowers 护花 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 493  Solved: 310[Submit][Status] Description Farmer John went to cut some wood and left N (2 <= N <= 100,000) cows eating the grass, as usual. When he retur…

[题目描述] 约翰留下他的N(N<=100000)只奶牛上山采木．他离开的时候,她们像往常一样悠闲地在草场里吃草．可是,当他回来的时候,他看到了一幕惨剧:牛们正躲在他的花园里,啃食着他心爱的美丽花朵!为了使接下来花朵的损失最小,约翰赶紧采取行动,把牛们送回牛棚． 牛们从1到N编号．第i只牛所在的位置距离牛棚Ti(1≤Ti≤2000000)分钟的路程,而在约翰开始送她回牛棚之前,她每分钟会啃食Di(1≤Di≤100)朵鲜花．无论多么努力,约翰一次只能送一只牛回棚．而运送第第i只牛事实上需要2Ti分…

Description Farmer John went to cut some wood and left N (2 <= N <= 100,000) cows eating the grass, as usual. When he returned, he found to his horror that the cows were in his garden eating his beautiful flowers. Wanting to minimize the subsequent…

P2878 [USACO07JAN]保护花朵Protecting the Flowers 难得的信息课......来一题水题吧. 经典贪心题 我们发现,交换两头奶牛的解决顺序,对其他奶牛所产生的贡献并没有影响. 我们设距离为$a_{i}$,每分钟贡献$b_{i}$ $a_{1}$        $b_{1}$ $a_{2}$        $b_{2}$ 先抓第一头的代价:$a_{1}b_{1}+2a_{1}b_{2}+a_{2}b_{2}$ 先抓第二头的代价:$a_{2}b_{2}+2a_{2…