题目链接 老天……终于碰上一个除了模板之外的LCA题了 这道题用Tarjan来LCA.树上两个点的路径是唯一的,所以钦定一个根,两点间的路径就是两点到根的路径减去双倍的公共祖先到根的路径.大概很好理解. #include<cstdio> #include<cctype> #include<cstring> #include<iostream> using namespace std; inline long long read(){ ,f=; char ch…

题目描述 The \(N\) cows (\(2 \leq N \leq 1,000\)) conveniently numbered \(1..N\) are grazing among the N pastures also conveniently numbered \(1..N\). Most conveniently of all, cow i is grazing in pasture i. Some pairs of pastures are connected by one of…

顾z 你没有发现两个字里的blog都不一样嘛 qwq 题目描述-->p2912 牧场散步 题意概括 给定一个树,给你Q个询问,每次询问输入一个二元组\((x,y)\),要求求出\((x,y)\)的距离. 明显带权lca. 这里写一下递推式 \[ f[u][i]=f[f[u][i-1]][i-1] \] \[ gw[u][i]=gw[f[u][i-1]][i-1]+gw[u][i-1] \] 定义: \(f[u][i]\)代表\(u\)向上跳\(2^i\)步到达的节点. \(gw[u][i]\)代…

题面:[USACO08OCT]牧场散步Pasture Walking 题解:LCA模版题 代码: #include<cstdio> #include<cstring> #include<iostream> using namespace std; ,max_log=; ][max_log+],edge_head[maxn+],num_edge=,c,Dep[maxn+],u,v,w,A,B; ]; struct Edge{ int to,nx,dis; }edge[(m…

P2912 [USACO08OCT]牧场散步Pasture Walking 求树上两点间路径--->lca 使用倍增处理lca(树剖多长鸭) #include<iostream> #include<cstdio> #include<cstring> #include<cctype> #define re register using namespace std; char gc(){ ],*p1=buf,*p2=buf; ,,stdin),p1==p2…

P2912 [USACO08OCT]牧场散步Pasture Walking 题目描述 The N cows (2 <= N <= 1,000) conveniently numbered 1..N are grazing among the N pastures also conveniently numbered 1..N. Most conveniently of all, cow i is grazing in pasture i. Some pairs of pastures are…

题目描述 The N cows (2 <= N <= 1,000) conveniently numbered 1..N are grazing among the N pastures also conveniently numbered 1..N. Most conveniently of all, cow i is grazing in pasture i. Some pairs of pastures are connected by one of N-1 bidirectional…

http://www.lydsy.com/JudgeOnline/problem.php?id=1602 || https://www.luogu.org/problem/show?pid=2912 题目描述 N头牛(2<=n<=1000)别人被标记为1到n,在同样被标记1到n的n块土地上吃草,第i头牛在第i块牧场吃草. 这n块土地被n-1条边连接. 奶牛可以在边上行走,第i条边连接第Ai,Bi块牧场,第i条边的长度是Li(1<=Li<=10000). 这些边被安排成任意两头奶牛都…

题目描述 The N cows (2 <= N <= 1,000) conveniently numbered 1..N are grazing among the N pastures also conveniently numbered 1..N. Most conveniently of all, cow i is grazing in pasture i. Some pairs of pastures are connected by one of N-1 bidirectional…

题目描述 The N cows (2 <= N <= 1,000) conveniently numbered 1..N are grazing among the N pastures also conveniently numbered 1..N. Most conveniently of all, cow i is grazing in pasture i. Some pairs of pastures are connected by one of N-1 bidirectional…