1672: [Usaco2005 Dec]Cleaning Shifts 清理牛棚 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 414  Solved: 191[Submit][Status] Description Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to…

题目 1672: [Usaco2005 Dec]Cleaning Shifts 清理牛棚 Time Limit: 5 Sec  Memory Limit: 64 MB Description Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most…

BZOJ_1672_[Usaco2005 Dec]Cleaning Shifts 清理牛棚_动态规划+线段树 题意:  约翰的奶牛们从小娇生惯养,她们无法容忍牛棚里的任何脏东西．约翰发现,如果要使这群有洁癖的奶牛满意,他不得不雇佣她们中的一些来清扫牛棚, 约翰的奶牛中有N(1≤N≤10000)头愿意通过清扫牛棚来挣一些零花钱．由于在某个时段中奶牛们会在牛棚里随时随地地乱扔垃圾,自然地,她们要求在这段时间里,无论什么时候至少要有一头奶牛正在打扫．需要打扫的时段从某一天的第M秒开始,到第E秒结束f0…

P4644 [Usaco2005 Dec]Cleaning Shifts 清理牛棚 你有一段区间需要被覆盖(长度 <= 86,399) 现有 \(n \leq 10000\) 段小线段, 每段可以从 \(l_{i}\) 到 \(r_{i}\) 花费为 \(s_{i}\) 求覆盖整个区间的最小花费 错误日志: 初始化时应该是 \(dp[L - 1]\) 为 \(0\) 而不是 \(dp[1]\) 为 \(0\) , 因为只需要覆盖 \([L, R]\) Solution 设 \(dp[n]\) 表…

[Usaco2005 Dec] Cleaning Shifts 清理牛棚 题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of th…

[BZOJ1672][Usaco2005 Dec]Cleaning Shifts Description Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire…

题目传送门 清理牛棚 题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of the cows to clean the barn.…

题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of the cows to clean the barn. Farmer John…

http://www.lydsy.com/JudgeOnline/problem.php?id=1672 dp很好想,但是是n^2的..但是可以水过..(5s啊..) 按左端点排序后 f[i]表示取第i个的最小费用 f[i]=min(f[j])+w[i] 当j的结束时间>=i的开始时间-1 答案就是所有的i满足i的结束时间>=结束时间-1 #include <cstdio> #include <cstring> #include <cmath> #inclu…

题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of the cows to clean the barn. Farmer John…

题目描述 Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer John, the most obliging of farmers, has no choice but hire some of the cows to clean the barn. Farmer John…

设f[i]为i时刻最小花费 把牛按l升序排列,每头牛能用f[l[i]-1]+c[i]更新(l[i],r[i])的区间min,所以用线段树维护f,用排完序的每头牛来更新,最后查询E点即可 #include<iostream> #include<cstdio> #include<algorithm> using namespace std; const int N=10005; const long long inf=1e18; int n,st,ed; struct xd…

链接 题意:给你一些区间,每个区间都有一个花费,求覆盖区间 \([S,T]\) 的最小花费 题解 先将区间排序 设 \(f[i]\) 表示决策到第 \(i\) 个区间,覆盖满 \(S\dots R[i]\) 的最小花费 显然 \(f[i]=\min_{R[j]\ge L[i]}f[j]+w[i]\) 按照区间建线段树,插右端点即可 #include<bits/stdc++.h> #define REP(i,a,b) for(int i(a);i<=(b);++i) using names…

[Usaco2005 Dec]Cleaning Shifts 给出n段区间,左右端点分别为\(l_i,r_i\),以及选取这段区间的费用\(c_i\),现在要选出若干个区间,使其完全覆盖区间\([m,e]\),询问费用之和的最小值,\(1≤n≤10000,0≤m≤e≤86399\). 解 法一: 不妨把区间按左端点排序,如果在大区间范围外,可以筛除,虽然题目有保障,于是设\(f_i\)表示以第i个区间结尾,覆盖第i个区间前所有需要覆盖的位置的最少代价,于是有 \[f_i=\min_{j=1,r_…

传送门 显然可以考虑 $dp$ 设 $f[i]$ 表示当前到了时间 $i$,从初始到 $i$ 的时间都安排好打扫了 把所有牛按照区间 $l,r$ 双关键字排序 这样枚举到一头牛 $x$ 时,在 $x.l$ 之前的牛都考虑完了($x.l$ 是牛 $x$ 的左区间) 然后枚举 $[x.l-1,x.r]$ 之间的时间 $y$,有转移 $f[x.r]=min(f[x.r],f[y]+x.c)$ ($x.r$ 是牛 $x$ 的右区间,$x.c$ 是牛$x$ 的花费) 这样转移才能保证从开始时间一直到 $x…

3389: [Usaco2004 Dec]Cleaning Shifts安排值班 Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 45  Solved: 26[Submit][Status] Description     一天有T(1≤T≤10^6)个时段．约翰正打算安排他的N(1≤N≤25000)只奶牛来值班,打扫 打扫牛棚卫生．每只奶牛都有自己的空闲时间段[Si,Ei](1≤Si≤Ei≤T),只能把空闲的奶牛安排出来值班．而且,每个时间段必需有…

3389: [Usaco2004 Dec]Cleaning Shifts安排值班 Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 218  Solved: 86[Submit][Status][Discuss] Description     一天有T(1≤T≤10^6)个时段．约翰正打算安排他的N(1≤N≤25000)只奶牛来值班,打扫 打扫牛棚卫生．每只奶牛都有自己的空闲时间段[Si,Ei](1≤Si≤Ei≤T),只能把空闲的奶牛安排出来值班．而…

题目 3389: [Usaco2004 Dec]Cleaning Shifts安排值班 Time Limit: 1 Sec  Memory Limit: 128 MB Description     一天有T(1≤T≤10^6)个时段．约翰正打算安排他的N(1≤N≤25000)只奶牛来值班,打扫 打扫牛棚卫生．每只奶牛都有自己的空闲时间段[Si,Ei](1≤Si≤Ei≤T),只能把空闲的奶牛安排出来值班．而且,每个时间段必需有奶牛在值班．  那么,最少需要动用多少奶牛参与值班呢?如果没有办法安排…

3389: [Usaco2004 Dec]Cleaning Shifts安排值班 Time Limit: 1 Sec  Memory Limit: 128 MBSubmit: 102  Solved: 46[Submit][Status][Discuss] Description     一天有T(1≤T≤10^6)个时段．约翰正打算安排他的N(1≤N≤25000)只奶牛来值班,打扫 打扫牛棚卫生．每只奶牛都有自己的空闲时间段[Si,Ei](1≤Si≤Ei≤T),只能把空闲的奶牛安排出来值班．而…

3389: [Usaco2004 Dec]Cleaning Shifts安排值班 Time Limit: 1 Sec  Memory Limit: 128 MB Description     一天有T(1≤T≤10^6)个时段．约翰正打算安排他的N(1≤N≤25000)只奶牛来值班,打扫 打扫牛棚卫生．每只奶牛都有自己的空闲时间段[Si,Ei](1≤Si≤Ei≤T),只能把空闲的奶牛安排出来值班．而且,每个时间段必需有奶牛在值班．  那么,最少需要动用多少奶牛参与值班呢?如果没有办法安排出合理…

http://www.lydsy.com/JudgeOnline/problem.php?id=3389 显然左端点排序后,依次取. 要考虑下一次取的方案: 待选点为a[j].x<=a[now].y+1的所有点j,其中now是当前所选 那么我们要在这些点内做决策 贪心就是取y最大的待选点,即 max(a[j].y)的j 实现中细节太多QAQ,写了挺久的.. #include <cstdio> #include <cstring> #include <cmath>…

题目:http://poj.org/problem?id=3171 题意:给你n个区间[a,b],每个区间都有一个费用c,要你用最小的费用覆盖区间[M,E] 分析:经典的区间覆盖问题,百度可以搜到这个专题. 线段覆盖问题一般考虑贪心和DP,但是每个区间又有了一个费用c,本渣觉得贪心貌似不太行(不知道神犇门有木有贪心解法),然后便考虑DP 设f[i]表示覆盖[M,i]的最小总费用 那么有f[t[i].a]=min(f[j]+t[i].c) t[i].a-1<=j<=t[i].b-1 那么ans=…

思路:可以贪心,也可以最短路. 贪心写法:因为在保证合法的前提下,我们选择的区间一定要右端点尽量靠后才行,于是我们每次就选择一个合法的并且右端点最靠后的区间就好了(如果没有合法的输出-1即可).时间复杂度O(nlogn)(排序是nlogn的,贪心是O(n)的). #include<cmath> #include<cstdio> #include<cstring> #include<iostream> #include<algorithm> usi…

Cleaning Shifts Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 4422   Accepted: 1482 Description Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer…

Cleaning Shifts Descriptions: 原文是English,我这就直接上Chinese了,想看原文的点一下链接哦 大表哥分配 N (1 <= N <= 25,000) 只中的一些奶牛在牛棚附近做些清洁. 他总是要让至少一只牛做清洁.他把一天分成T段(1 <= T <= 1,000,000), 第一段是1,最后一段是T 每只奶牛只在一些时间段有空.奶牛如果选择某一段时间,则必须完成整段时间的工作 你的任务是帮助FJ安排一些奶牛,使每段时间至少有一只奶牛被安排来做…

[Usaco2005 Dec]Knights of Ni 骑士 Description  贝茜遇到了一件很麻烦的事:她无意中闯入了森林里的一座城堡,如果她想回家,就必须穿过这片由骑士们守护着的森林．为了能安全地离开,贝茜不得不按照骑士们的要求,在森林寻找一种特殊的灌木并带一棵给他们．当然,贝茜想早点离开这可怕的森林,于是她必须尽快完成骑士们给的任务,贝茜随身带着这片森林的地图,地图上的森林被放入了直角坐标系,并按x,y轴上的单位长度划分成了W×H(1≤W,H≤1000)块,贝茜在地图上查出了她自…

http://poj.org/problem?id=2376 Cleaning Shifts Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 12604   Accepted: 3263 Description Farmer John is assigning some of his N (1 <= N <= 25,000) cows to do some cleaning chores around the barn.…

POJ 2376 Cleaning Shifts(轮班打扫) Time Limit: 1000MS   Memory Limit: 65536K [Description] [题目描述] Farmer John is assigning some of his N (1 <= N <= 25,000) cows to do some cleaning chores around the barn. He always wants to have one cow working on clean…

Cleaning Shifts 题目连接: http://poj.org/problem?id=2376 Description Farmer John is assigning some of his N (1 <= N <= 25,000) cows to do some cleaning chores around the barn. He always wants to have one cow working on cleaning things up and has divided…

Cleaning Shifts Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 2743   Accepted: 955 Description Farmer John's cows, pampered since birth, have reached new heights of fastidiousness. They now require their barn to be immaculate. Farmer J…