[题目链接] https://www.lydsy.com/JudgeOnline/problem.php?id=3363 [算法] 树的直径 [代码] #include<bits/stdc++.h> using namespace std; #define MAXN 100010 struct edge { int to,w,nxt; } e[MAXN << ]; int i,n,m,u,v,w,ans,tot; ]; int head[MAXN],d[MAXN]; inline…

3363: [Usaco2004 Feb]Cow Marathon 奶牛马拉松 Description ​ 最近美国过度肥胖非常普遍,农夫约翰为了让他的奶牛多做运动,举办了奶牛马拉松．马拉 松路线要尽量长,所以,告诉你农场的地图(该地图的描述与上题一致),请帮助约翰寻找两个 最远农场间的距离． Input ​ 第1行:两个分开的整数N和M. ​ 第2到M+1行:每行包括4个分开的内容,Fi,F2,L,D分别描述两个农场的编号,道路的长 度,F1到F2的方向N,E,S,W． Output ​ 一个…

Cow Marathon Time Limit: 2000MS   Memory Limit: 30000K Total Submissions: 3195   Accepted: 1596 Case Time Limit: 1000MS Description After hearing about the epidemic of obesity in the USA, Farmer John wants his cows to get more exercise, so he has com…

题目连接 http://poj.org/problem?id=1985 Cow Marathon Description After hearing about the epidemic of obesity in the USA, Farmer John wants his cows to get more exercise, so he has committed to create a bovine marathon for his cows to run. The marathon ro…

Cow Marathon Time Limit: 2000MS   Memory Limit: 30000K Total Submissions: 4185   Accepted: 2118 Case Time Limit: 1000MS Description After hearing about the epidemic of obesity in the USA, Farmer John wants his cows to get more exercise, so he has com…

Cow Marathon Time Limit: 2000MS   Memory Limit: 30000K Total Submissions: 5496   Accepted: 2685 Case Time Limit: 1000MS Description After hearing about the epidemic of obesity in the USA, Farmer John wants his cows to get more exercise, so he has com…

传送门 Cow Marathon Time Limit: 2000MS   Memory Limit: 30000K Total Submissions: 5362   Accepted: 2634 Case Time Limit: 1000MS Description After hearing about the epidemic of obesity in the USA, Farmer John wants his cows to get more exercise, so he has…

[BZOJ 3307]Cow Politics (LCA) 题面 给出一棵N个点的树,树上每个节点都有颜色.对于每种颜色,求该颜色距离最远的两个点之间的距离.N≤200000 分析 显然对于每种颜色建立一棵虚树是可行的.但是有编码复杂度更低的方法.显然某种颜色距离最远的两个点中,一个肯定是这种颜色的点中深度最深的(贪心考虑,如果还有更深的,那么选更深的一定更优).那么我们只要找出每种颜色深度最深的点,然后向该种颜色的每一个点暴力求距离即可. 由于所有颜色的点的个数加起来为n,总时间复杂度\(O(…

Description 给你一个图,两个点至多有一条路径,求最长的一条路径. \(n \leqslant 4\times 10^4\) Sol DFS?DP? 这就是一棵树,方向什么的都没用... 然后记录一下到这个点的最大值和次大值更新答案即可. Code /************************************************************** Problem: 3363 User: BeiYu Language: C++ Result: Accepted…

题目大意:给出一棵树.求两点间的最长距离. 思路:裸地树的直径.两次BFS,第一次随便找一个点宽搜.然后用上次宽搜时最远的点在宽搜.得到的最长距离就是树的直径. CODE: #include <queue> #include <cstdio> #include <cstring> #include <iostream> #include <algorithm> #define MAX 80010 using namespace std; int…