1# include<iostream>2# include<bits/stdc++.h>3usingnamespacestd;4# defineintlonglong5# define endl"\n"6constintN = 2e5 +10;7vector<int>g[N];8ints[N];9intc[N];10map<pair<int,int>,int>mp;11intf[N][2];12intd[N];13intdfs2(intu,intF) {14d[u] =g[u].size();15if(d...
F. Three Paths on a Tree(树的直径) https://codeforces.com/contest/1294/problem/F 思路: 思路还是比较好想的。 取两个点放到直径,必然是最优的。剩下一个算距离最大的就好。 所以开始我是把直径的点标记了。然后最后扫的时候再算一下到lca(i,A),lca(i,B)去更新最值。但是一直wa。 最后索性改...
先说结论,选出的三个点必定有两个点是树的直径上的两个端点,如果给出的树是一条链,结论必定成立,下面是给出的树不是链的时候的证明。 设三个点分别为a,b,c,设每条边的边权为1,那么答案就是dis(a,b)+dis(a,c)+dis(b,c)。如果给出的树不是一条链,那么a,b,c三点之间必然由一...
A tree decomposition in paths is valid if each vertex belongs to exactly one path. A path can be a single vertex. Two decompositions are different if there are two vertices and that belong to the same path in one of the decompositions but two distinct paths in the other. Sample Input: 5...
It is guaranteed that the sum of the values nn over all test cases in the test does not exceed 2⋅1052⋅105. For each test case on the first line, output an integer mm— the minimum number of non-intersecting leading down paths that can cover all vertices of the tree. Then print...
Consider a path from the root of the tree to a leaf. The characters on the edges on this path form a string, we say that this string is associated with this leaf. The tree is anagrammable if and only if it is possible to replace each question mark with a lowercase English letter so...
技术标签: DP动态规划 dsu on tree Dsu on Tree 状态压缩Codeforces Round #383 (Div. 1) D 着实难做! 首先,题意,题意不是一棵子树上任意构成!!! 题意: 问的是对应子树v,它上面的简单路径(链),所能构成的最长的回文长度。然后输出对应的1～N的所有以它为子树根结点的最长回文长度(不强制要求经过根...
Path i is denoted by two integers ai and bi, the labels of the endpoints (1 ≤ ai, bi ≤ n). For some paths, it may be that ai = bi. It is not guaranteed that all paths are pairwise distinct. Output On the first line, print the size of the best subset of ...
分析:显然的dsu on the tree,不带修改操作,又只涉及到子树查询,只是细节比较麻烦. 满足要求的路径就是至多只有一个出现奇数次数字符,因为字符只可能是a ~ v,共22个字符,所以可以用二进制数存状态,0/1表示出现了偶数次/奇数次. s[i]表示1到i号点的路径的状态. f[i]表示状态为i的点的最深深度,h[i]表...
Arpa has a rooted tree (connected acyclic graph) consisting ofnvertices. The vertices are numbered1throughn, the vertex1is the root. There is a letter written on each edge of this tree. Mehrdad is a fan ofDokhtar-koshthings. He call a string Dokhtar-kosh, if we can shuffle the character...