摘要："洛咕" 分析:题目要求删去一条边后最长路径最短,显然是要二分答案.假设当前二分了最长路径长度为$mid$,那么$m$条路径中,所有长度大于$mid$的路径,都要删去它们的最长的公共边.这条公共边要怎么求?树上差分 边差分.如果减去这条最长公共边之后所有的路径长度都小于等于$mid$,就说明二分合法 阅读全文

摘要："洛咕" 题意:给定一棵$n(n include include include include include include include define ll long long using namespace std; inline int read(){ int x=0,o=1;char 阅读全文

摘要："洛咕" 题意:给定一棵$n(n include include include include include include include define ll long long using namespace std; inline int read(){ int x=0,o=1;char 阅读全文

摘要："洛咕" 题意:给定有$n$个节点的树, 树上边有边权. 再给定$q$组询问, 每次询问两个点路径上的最小值和最大值.$n,q include include include include include include include define ll long long using name 阅读全文

摘要："洛咕" 题意:一棵有根树，多次询问这棵树上一段路径上所有节点深度的$k$次方的和，每次的$k$可能是不同的.此处节点深度的定义是这个节点到根的路径上的边数.$n,m include include include include include include include define ll 阅读全文

摘要："洛咕" 题意:给定一棵$n(n include include include include include include include define ll long long using namespace std; inline int read(){ int x=0,o=1;char 阅读全文

摘要："洛咕" 题意:给定一张$n$个点$m$条边的无向图,求无向图的严格次小生成树.$ny$路径上的最大边权$maxx$,则答案可以更新为$ans=min(ans,sum maxx+z)$,相当于删去这条边权最大的边,加入我们当前枚举的这条边,从而保证严格次小. $long$ $long$ cpp in 阅读全文

摘要："AcWing 异象石" "洛咕 寻宝游戏" 题意:Adera是Microsoft应用商店中的一款解谜游戏. 异象石是进入Adera中异时空的引导物，在Adera的异时空中有一张地图. 这张地图上有$N(N include include include include include includ 阅读全文

摘要："POJ" 题意:给定一棵$n(n=2$,表示切掉这条树边,这条树边仍在环上,第二次怎么切都无法切成两个联通块,故不对不产生贡献. cpp include include include include include include include include define ll long l 阅读全文

摘要："洛咕" 题意:A国有n座城市，编号从1到n，城市之间有m条双向道路.每一条道路对车辆都有重量限制，简称限重.现在有q辆货车在运输货物，司机们想知道每辆车在不超过车辆限重的情况下，最多能运多重的货物? 分析:题意就是找到给定两点之间的一条路径,使得最小边权最大.所以我们先构建出图的一棵最大生成树(因 阅读全文

摘要：LCA指的是最近公共祖先,更具体的意义就不讲了. 求解LCA的方法有很多,这里讲解向上标记法,树上倍增法,tarjan求LCA. 向上标记法 1 从x向上走到根节点,并标记所有经过的节点. 2 从y向上走到根节点,第一次遇到的已标记的节点就是x和y的LCA. 但不难发现,这个算法只适用于求一个点和一 阅读全文