这题和金华区域赛A题(HDU 4442)是一样的做法. 对两个奶牛进行分析,选择两个奶牛总花费少的方式排序. bool cmp(const X&a,const X&b){ return a.t*b.d<b.t*a.d;} #include<cstdio> #include<cstring> #include<cmath> #include<algorithm> using namespace std; +; struct X { lon…

http://poj.org/problem?id=3262 Protecting the Flowers Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 4930   Accepted: 1965 Description Farmer John went to cut some wood and left N (2 ≤ N ≤ 100,000) cows eating the grass, as usual. When…

Protecting the Flowers Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 7812   Accepted: 3151 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 ho…

Protecting the Flowers Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 11402   Accepted: 4631 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 h…

http://poj.org/problem?id=3262 开始一直是理解错题意了!!导致不停wa. 这题是农夫有n头牛在花园里啃花朵,然后农夫要把它们赶回棚子,每次只能赶一头牛,并且给出赶回每头牛需要的时间和牛在花园每分钟吃多少花朵,问你怎么安排让损失最小. 这题单独按time和eat排序都不行,得按它们的比率来排,如果是选择eat/time  则从大到小排,time/eat则从小到大排,但是不会严格证明. #include <iostream> #include <cstdio&g…

题意:给定n个奶牛,FJ把奶牛i从其位置送回牛棚并回到草坪要花费2*t[i]时间,同时留在草地上的奶牛j每分钟会消耗d[j]个草 求把所有奶牛送回牛棚内,所消耗草的最小值 思路:贪心,假设奶牛a和奶牛b所处位置为, 交换前 ....(ta, da) (tb, db).... 交换后 ....(tb, db) (ta, da).... 设此前已消耗的时间为x,那么交换前消耗的草:x*da + (x+ta)*db 交换后消耗的草:x*db + (x+tb)*da 除非交换后的消耗相比交换前的小才交换…

题意:有n个牛在FJ的花园乱吃.所以FJ要赶他们回牛棚.每个牛在被赶走之前每秒吃Di个花朵.赶它回去FJ来回要花的总时间是Ti×2.在被赶走的过程中,被赶走的牛就不能乱吃 思路: 先赶走破坏力大的牛假设序列都由二元组组成,二元组是由T和D组成,那么对一个序列有相邻的两头牛是这样的..........(a, b) ,(c, d)....................如果(a,b)和(c,d)交换位置了变成新序列..........(c,d),(a,b)......................…

Protecting the Flowers 直接中文 Descriptions FJ去砍树,然后和平时一样留了 N (2 ≤ N ≤ 100,000)头牛吃草.当他回来的时候,他发现奶牛们正在津津有味地吃着FJ种的美丽的花!为了减少后续伤害,FJ决定立即采取行动:运输每头牛回到自己的牛棚. 每只奶牛i在离牛棚Ti(1 ≤ Ti ≤ 2,000,000) 分钟路程的地方,每分钟吃掉Di(1 ≤ Di ≤ 100)朵花.FJ使尽浑身解数,也只能一次带回一头奶牛.弄回一头奶牛i需要2*Ti分钟(来回…

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…

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 ,…