题意: 给定n个城市的货物买卖价格, 然后给定n-1条道路,每条路有不同的路费, 求出从某两个城市买卖一次的最大利润. 利润 = 卖价 - (买价 + 路费) 样例数据, 最近是从第一个点买入, 第4个点卖出, 利润为8 分析: 1.如果一条边连接(u,v),路费为cost ,城市买卖价格用P( )表示, 那么他的边权就表达为(P(v) - P(u) - cost). 2.我们可以假设有一个起点.他连接着所有的点,边权为0. 3.那么如果从这个点出发的话, 就等于是把所有的城市都尝试作为买入城市…

1.图类基本组成 存储在邻接表中的基本项 /** * Represents an edge in the graph * */ class Edge implements Comparable<Edge> { public Vertex dest; //Second vertex in Edge public double cost; //Edge cost public Edge(Vertex d, double c) { dest = d; cost = c; } @Override pu…

[问题描述] 对于一个带负权值边的有向图,实现Bellman-Ford算法,求出从指定顶点s到其余顶点的最短路径,并判断图中是否存在负环. package org.xiu68.exp.exp10; public class Exp10_1 { public static void main(String[] args) { // TODO Auto-generated method stub int[][] edges=new int[][]{ {0,10,0,4,1}, {0,0,0,0,0}…

transaction transaction transaction Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 132768/132768 K (Java/Others) Total Submission(s): 88    Accepted Submission(s): 39 Problem Description Kelukin is a businessman. Every day, he travels around…

https://vjudge.net/contest/184514#problem/H 题意: 一个商人为了赚钱,在城市之间倒卖商品.有n个城市,每个城市之间有且只有一条无向边连通.给出n个城市的货物的价格,比如A城市是a元,B城市是b元,那么在A买在B卖,赚的钱就是b - a,反之就是 a - b.商人走每条路也需要一定的花费.现在他需要选择某两个城市进行货物的倒卖,问他能获得的最大利润是多少. 思路: 建图的方式非常妙.我们把从A到B的边的权值定义为b - a - v(v为边的权值),从B到…

SPFA(Shortest Path Faster Algorithm)是Bellman-Ford算法的一种队列实现,减少了不必要的冗余计算. 算法大致流程是用一个队列来进行维护. 初始时将源加入队列. 每次从队列中取出一个元素,并对所有与他相邻的点进行松弛,若某个相邻的点松弛成功,则将其入队. 直到队列为空时算法结束. 这个算法,简单的说就是队列优化的bellman-ford,利用了每个点不会更新次数太多的特点发明的此算法 SPFA--Shortest Path Faster Algorith…

Description While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way path that delivers you to its destination at a time that is BEFORE you entered the wormhole! Eac…

Wormholes Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 36717   Accepted: 13438 Description While exploring his many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it is a one-way p…

transaction transaction transaction Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 132768/132768 K (Java/Others)Total Submission(s): 895    Accepted Submission(s): 441 Problem Description Kelukin is a businessman. Every day, he travels aroun…

transaction transaction transaction Kelukin is a businessman. Every day, he travels around cities to do some business. On August 17th, in memory of a great man, citizens will read a book named "the Man Who Changed China". Of course, Kelukin woul…