P2966 [USACO09DEC]牛收费路径Cow Toll Paths 题目描述 Like everyone else, FJ is always thinking up ways to increase his revenue. To this end, he has set up a series of tolls that the cows will pay when they traverse the cowpaths throughout the farm. The cows mo…

[题意概述] 给出一个图,点有正点权,边有正边权,通过两点的代价为两点间的最短路加上路径通过的点的点权最大值. 有M个询问,每次询问通过两点的代价. [题解] 先把点按照点权从小到大排序,然后按照这个顺序跑floyed.  这样的话当前路径i-->k-->j的点权最大值只会在i,j,k中产生,用一个ans[i][j]数组维护代价即可. #include<cstdio> #include<algorithm> #include<cstring> #define…

题目描述 Like everyone else, FJ is always thinking up ways to increase his revenue. To this end, he has set up a series of tolls that the cows will pay when they traverse the cowpaths throughout the farm. The cows move from any of the N (1 <= N <= 250)…

题目描述 Like everyone else, FJ is always thinking up ways to increase his revenue. To this end, he has set up a series of tolls that the cows will pay when they traverse the cowpaths throughout the farm. The cows move from any of the N (1 <= N <= 250)…

跟所有人一样,农夫约翰以着宁教我负天下牛,休叫天下牛负我的伟大精神,日日夜夜苦思生 财之道.为了发财,他设置了一系列的规章制度,使得任何一只奶牛在农场中的道路行走,都 要向农夫约翰上交过路费. 农场中由N(1 <= N <= 250)片草地(标号为1到N),并且有M(1 <= M <= 10000)条 双向道路连接草地A_j和B_j(1 <= A_j <= N; 1 <= B_j <= N). 奶牛们从任意一片草 地出发可以抵达任意一片的草地.FJ已经在连接…

原题全英文的,粘贴个翻译题面,经过一定的修改. 跟所有人一样,农夫约翰以宁教我负天下牛,休叫天下牛负我的伟大精神,日日夜夜苦思生财之道.为了发财,他设置了一系列的规章制度,使得任何一只奶牛在农场中的道路行走,都要向农夫约翰上交过路费. 农场中由N(1 <= N <= 250)片草地(标号为1到N),并且有M(1 <= M <= 10000)条双向道路连接草地i和j(1 <= i,j <= N). 奶牛们从任意一片草地出发可以抵达任意一片的草地.FJ已经在连接i和j的双向…

https://www.luogu.org/problem/P2966 题目描述 Like everyone else, FJ is always thinking up ways to increase his revenue. To this end, he has set up a series of tolls that the cows will pay when they traverse the cowpaths throughout the farm. The cows move…

很妙的一道题,我之前一直是用一个非常暴力的做法 就是枚举点权跑堆优化dijkstra 但是询问次数太多了 于是一直只有50分 今天终于抄做了这道题,不贴代码了,只说一下对这道题的理解 首先点权和边权不能混在一起,这是公认的,毕竟这个样子完全没有办法处理 那我们为什么要排序呢,发现其余几篇题解好像也没讲清楚 说得好像我能讲清楚一样 我们对于所有点按点权进行了一个排序,这一点很令人玩味,这是为什么呢 首先我们的floyd的枚举是长这个样子的 for(re int k=1;k<=n;k++) for(…

洛谷P1522 [USACO2.4]牛的旅行 Cow Tours 题意: 给出一些牧区的坐标,以及一个用邻接矩阵表示的牧区之间图.如果两个牧区之间有路存在那么这条路的长度就是两个牧区之间的欧几里得距离. 对于一个联通块,称之为一个牧场,也就是说一个牧场内任意一个牧区都可以到达该牧场内的任意的另外一个牧区. 对于一个牧场,它的直径是这个联通块内最短路的最大值. 现在让你在恰当地选择两个牧场,在这两个牧场中各自选一个牧区,在这两个牧区之间建路,要求建路之后所有牧场中最大的直径最小.这里其实如果产生了…

P1821 [USACO07FEB]银牛派对Silver Cow Party 题目描述 One cow from each of N farms (1 ≤ N ≤ 1000) conveniently numbered 1..N is going to attend the big cow party to be held at farm #X (1 ≤ X ≤ N). A total of M (1 ≤ M ≤ 100,000) unidirectional (one-way roads co…