POJ.1986 Distance Queries ( LCA 倍增 ) 题意分析 给出一个N个点,M条边的信息(u,v,w),表示树上u-v有一条边,边权为w,接下来有k个询问,每个询问为(a,b),求a,b两点到lca(a,b)的边权之和为多少. 倍增维护树上前缀和,求得LCA之后,相应做差即可. 代码总览 #include <cstdio> #include <algorithm> #include <cstring> #include <cmath>…

Home » Practice(Hard) » Dynamic Trees and Queries Problem Code: ANUDTQSubmit https://www.codechef.com/problems/ANUDTQ Tweet   All submissions for this problem are available. Read problems statements in Mandarin Chineseand Russian. Given a directed tr…

由于可以走重边,所以任意一条路径长 + 2 仍然对应至少一条合法路径 很显然我们有 \(3\) 种基本路径 不经过 \((x,y)\) 经过 \(x \to y\) 经过 \(y \to x\) 假设某个基本路径的答案是 \(d\),询问是 \(k\),如果同时满足以下条件,则该基本路径可以作为答案 \(d \leq k\) \(d = k \ (mod \ 2)\) 于是暴力做即可 #include <bits/stdc++.h> using namespace std; const int…

题目链接:http://poj.org/problem?id=1986 Farmer John's cows refused to run in his marathon since he chose a path much too long for their leisurely lifestyle. He therefore wants to find a path of a more reasonable length. The input to this problem consists…

Distance Queries [题目链接]Distance Queries [题目类型]LCA Tarjan法 &题意: 输入n和m,表示n个点m条边,下面m行是边的信息,两端点和权,后面的那个字母无视掉,没用的.接着k,下面k个询问lca,输出即可 &题解: 首先看的这个 http://www.cnblogs.com/JVxie/p/4854719.html 大致懂了方法,之后又找了这个代码 http://blog.csdn.net/lianai911/article/details…

题目链接:http://poj.org/problem?id=1986 Description Farmer John's cows refused to run in his marathon since he chose a path much too long for their leisurely lifestyle. He therefore wants to find a path of a more reasonable length. The input to this prob…

题目链接: Distance Queries Time Limit: 2000MS   Memory Limit: 30000K Total Submissions: 11531   Accepted: 4068 Case Time Limit: 1000MS Description Farmer John's cows refused to run in his marathon since he chose a path much too long for their leisurely l…

标题来源:POJ 1986 Distance Queries 意甲冠军:给你一棵树 q第二次查询 每次你问两个点之间的距离 思路:对于2点 u v dis(u,v) = dis(root,u) + dis(root,v) - 2*dis(roor,LCA(u,v)) 求近期公共祖先和dis数组 #include <cstdio> #include <cstring> #include <vector> using namespace std; const int max…

解题关键:LCA模板题 复杂度:$O(n\log n)$ #pragma comment(linker, "/STACK:1024000000,1024000000") #include<cstdio> #include<cstring> #include<algorithm> #include<cstdlib> #include<cmath> #include<iostream> typedef long lon…

前言 这场比赛,在最后 \(5\) 分钟,我想到了这道题的 \(Idea\),但是,没有打完,比赛就结束了. 正文 题目意思 这道题目的意思就是说,一棵树上每次给 \(x\) 和 \(y\) 节点连 \(1\) 条边,问 \(a\) 到 \(b\) 之间有没有长度为 \(k\) 的边. 分析 一开始,我看到这道题就往基环树这里去想,可实际上,这道题的方法却是和加工零件这道题是有异曲同工之处,作者那道题里面也写了篇题解,不会的同学可以去看一看. 这道题难处理的地方就是加 \(1\) 条边这个地方很…