1671: [Usaco2005 Dec]Knights of Ni 骑士 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 281  Solved: 180[Submit][Status][Discuss] Description Bessie is in Camelot and has encountered a sticky situation: she needs to pass through the forest that is guarde…

Description Bessie is in Camelot and has encountered a sticky situation: she needs to pass through the forest that is guarded by the Knights of Ni. In order to pass through safely, the Knights have demanded that she bring them a single shrubbery. Tim…

[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…

1671: [Usaco2005 Dec]Knights of Ni 骑士 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 254  Solved: 163[Submit][Status][Discuss] Description Bessie is in Camelot and has encountered a sticky situation: she needs to pass through the forest that is guarde…

1671: [Usaco2005 Dec]Knights of Ni Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 175  Solved: 107[Submit][Status][Discuss] Description Bessie is in Camelot and has encountered a sticky situation: she needs to pass through the forest that is guarded b…

http://www.lydsy.com/JudgeOnline/problem.php?id=1671 从骑士bfs一次,然后从人bfs一次即可. #include <cstdio> #include <cstring> #include <cmath> #include <string> #include <iostream> #include <algorithm> #include <queue> using na…

Description Bessie is in Camelot and has encountered a sticky situation: she needs to pass through the forest that is guarded by the Knights of Ni. In order to pass through safely, the Knights have demanded that she bring them a single shrubbery. Tim…

Description Bessie is in Camelot and has encountered a sticky situation: she needs to pass through the forest that is guarded by the Knights of Ni. In order to pass through safely, the Knights have demanded that she bring them a single shrubbery. Tim…

题目: https://www.lydsy.com/JudgeOnline/problem.php?id=1671 题解: 按题意分别从贝茜和骑士bfs然后meet_in_middle.. 把一个逗号打成分号调了20分钟... 代码: #include<bits/stdc++.h> using namespace std; ]={,-,,,},my[]={,,,-,}; ; int n,m,g[maxn][maxn],vis[maxn][maxn],f[maxn][maxn],sum,cnt,…

bfs预处理出每个点s和t的距离d1和d2(无法到达标为inf),然后在若干灌木丛格子(x,y)里取min(d1[x][y]+d2[x][y]) /* 0:贝茜可以通过的空地 1:由于各种原因而不可通行的区域 2:贝茜现在所在的位置 3:骑士们的位置 4:长着贝茜需要的灌木的土地 */ #include<iostream> #include<cstdio> #include<queue> #include<cstring> using namespace s…

搞了半天八数码弄不出来就只好来打题解  这道题是在搜索a碰到的(链接: http://pan.baidu.com/s/1jG9rQsQ ) 感觉题目最大亮点就是这英文简写"ni", 真是令人感慨出题老师的才华啊  好了,废话不多说  题目内容如下(闲烦请无视之,下下方有简单的介绍): [问题描述] 贝 西(Bessie)在卡摩洛遇到了棘手的情况:她必须穿越由Ni骑士把守的森林. 骑士答应Bessie只要 Bessie 能给他们带来一丛灌木就能安全穿越森林.时间宝贵,Bessie 必须尽…

[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…

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…

[BZOJ1731][Usaco2005 dec]Layout 排队布局 Description Like everyone else, cows like to stand close to their friends when queuing for feed. FJ has N (2 <= N <= 1,000) cows numbered 1..N standing along a straight line waiting for feed. The cows are standin…

[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_…

1731: [Usaco2005 dec]Layout 排队布局 题意: n头奶牛在数轴上,不同奶牛可以在同个位置处,编号小的奶牛必须在前面.m条关系,一种是两头奶牛距离必须超过d,一种是两头奶牛距离不能超过d.要求:如果不存在情况满足要求则输出-1,奶牛1到n的距离可以为无限大输出-2,否则输出1到n的最大距离. 题解: 差分约束系统.注意:如果是求最大值,则定义限制条件设定为≤并跑最短路,因为得到的是满足条件的最大值,如果是求最小值,则定义限制条件设定为≥并跑最长路,因为得到的是满足条件的最…

bzoj1673[Usaco2005 Dec]Scales 天平 题意: n个砝码,每个砝码重量大于前两个砝码质量和,天平承重为c,求天平上最多可放多种的砝码.n≤1000,c≤2^30. 题解: 斐波那契数列到30多项就爆int了,所以本题n其实≤30.故爆搜即可,加个剪枝:当前选的砝码质量和+剩下砝码质量和仍≤ans就返回. 代码: #include <cstdio> #include <cstring> #include <algorithm> #define i…

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…

题意:一个人要从2先走到4再走到3,计算最少路径. 析:其实这个题很水的,就是要注意,在没有到4之前是不能经过3的,一点要注意.其他的就比较简单了,就是一个双向BFS,先从2搜到4,再从3到搜到4, 然后求最短路即可. 代码如下: #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstr…

[问题描述] Czy喜欢将他的妹子们排成一队.假设他拥有N只妹纸,编号为1至N.Czy让他们站成一行,等待自己来派送营养餐.这些妹纸按照编号大小排列,并且由于它们都很想早点吃饭,于是就很可能出现多只妹纸挤在同一位置的情况(也就是说,如果我们认为妹纸位于数轴上,那么多只妹纸的位置坐标可能相同). 因为众所周知的原因,某些妹纸之间互相喜欢,他们希望互相之间的距离至多为一个定值.但某些妹纸之间互相厌恶,他们希望互相之间的距离至少为一个定值.现在给定ML个互相喜爱的妹纸对以及他们之间距离的最大值,MD个…

Description 约翰的N(1≤N≤100000)只奶牛中出现了K(1≤K≤25000)只爱惹麻烦的坏蛋．奶牛们按一定的顺序排队的时候,这些坏蛋总会站在一起．为了找出这些坏蛋,约翰让他的奶牛排好队进入牛棚,同时需要你的慧眼来识别坏蛋,为了区分,约翰给所有奶牛都发了号牌,上面写着一个1．．S(1≤S≤25)之间的数字．虽然这不是一个完美的方法,但也能起一点作用．现在,约翰已经不记得坏蛋们的具体号码．但是凭他的记忆,他给出一个"模式串"．原坏蛋的号码如果相同,模式串中他们的号码依然相…

Description Farmer John has a balance for weighing the cows. He also has a set of N (1 <= N <= 1000) weights with known masses (all of which fit in 31 bits) for use on one side of the balance. He places a cow on one side of the balance and then adds…

差分约束系统...因为题目要求的是1和n的最大距离所以这题就跑最长路.. 对于互相反感的牛(i与j互相反感,彼此距离至少为len,i<j),就有dis[j]-dis[i]>=len.就加一条i->j,长度为len的边. 有好感的牛(i与j有好感,彼此距离至多len,i<j),就有dis[j]-dis[i]<=len;但因为我们跑的是最长路,所以得改成dis[i]-dis[j]>=-len的形式,就加一条j->i,长度-len的边. 又因为牛是按编号站成一列..所以…

填坑- 差分约束一般是搞一个不等式组,求xn-x1的最大最小值什么的,求最大值就转化成xa<=xb+w这样的,然后建图跑最短路(这才是最终约束的),举个例子 x1<=x0+2x2<=x0+7x3<=x0+8x2<=x1+3x3<=x2+2 那么解出来 x3<=x0+7x3<=x0+8x3<=x0+9 结果肯定是 x3<=x0+7 所以直接对于已知条件建边,大于小于可以互相转换,注意:相邻的要保证顺序. #include<cstdio>…

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.…

http://www.lydsy.com/JudgeOnline/problem.php?id=1673 bzoj翻译过来的c<=230不忍吐槽................................. 这题很奇葩.. 因为这些数像fib数一样递增,所以n<=45...................... ... dfs背包即可... #include <cstdio> #include <cstring> #include <cmath> #in…