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…

题意描述 Cow Toll Paths G 这道题翻译的是真的不错,特别是第一句话 给定一张有 \(n\) 个点 \(m\) 条边的无向图,每条边有边权,每个点有点权. 两点之间的路径长度为所有边权 + 点权的最大值,求 \(q\) 组 \(s\to t\) 的最短路径. 算法分析 数据范围 \(n\leq 250\)(和谐数字)Floyd 乱搞没跑了. 但是这道题唯一与普通全源最短路的不同之处在于,这道题要求一个最大点权. 一开始我的想法是二分找最小点权,就是每次只走点权 < mid 的点跑…

啊好气 在洛谷上A了之后 隔壁jzoj总wa 迷茫了很久.发现那题要文件输入输出 生气 肥肠不爽 Description 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 <=…

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)…

题目大意:给定 N 个节点,M 条边的无向图,边有边权,点有点权,现给出 Q 个询问,每个询问查询两个节点之间的最短路径,这里最短路径的定义是两个节点之间的最短路径与这条路径中经过的节点点权的最大值之和. 题解:多源最短路问题应该用 floyd 算法来处理,由于最短路径涉及到路径中最大的点权,因此如何在决策阶段快速进行状态转移是这道题考虑的核心.若每次进行枚举点权,复杂度显然爆炸.因此在开始时对点权进行排序,这样对于带点权的最短路径的决策仅由 i,j,k 三个点点权的最大值决定,时间复杂度为 \…

[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)…

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…

https://www.luogu.org/problem/show?pid=2966 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 c…