题意:问有多少条路径,符合路径上所有节点的权值乘积模1000003等于k. 解题关键:预处理阶乘逆元,然后通过hash和树形dp$O(1)$的判定乘积存在问题,注意此道题是如何处理路径保证不重复的,具有启发意义. 代码:2340ms,这段代码最重要的可取点就是如何通过操作省去memset的过程 复杂度:$O(n\log n)$ #pragma comment(linker,"/STACK:102400000,102400000") #include<cstdio> #inc…

题目大概说给一棵有点权的树,输出字典序最小的点对,使这两点间路径上点权的乘积模1000003的结果为k. 树的点分治搞了.因为是点权过根的两条路径的LCA会被重复统计,而注意到1000003是质数,所以这个用乘法逆元搞一下就OK了.还有要注意“治”的各个实现,把时间复杂度“控制”在O(nlogn). WA了几次,WA在漏了点到子树根的路径,还有每次分治忘了清空数组. #include<cstdio> #include<cstring> #include<algorithm&g…

D树 时间限制:10000/5000 MS(Java / Others)内存限制:102400/102400 K(Java / Others) 总共提交5400个已接受的提交1144 问题描述 南京理工大学的操场上站着一棵高大的树.在树的每个分支上是一个整数(树可以被看作是一个有N个顶点的连通图,而每个分支可以被当作一个顶点).今天,树下的学生正在考虑一个问题:我们可以在树上找到这样一个链,使链上所有整数(mod 10 6 + 3)的乘积等于K? 你能帮助他们解决这个问题吗?   输入 有几个测…

思路比较裸,但是要把答案存到哈希表里面,这里需要一定技巧,否则会被K=1且点权全是1的数据卡飞.预处理乘法逆元.TLE了一天.换了种点分治的姿势…… #pragma comment(linker,"/STACK:102400000,102400000") #include<cstdio> #include<algorithm> #include<cstring> using namespace std; int Res;char C; inline…

1468: Tree Time Limit: 10 Sec  Memory Limit: 64 MBSubmit: 1025  Solved: 534[Submit][Status][Discuss] Description 给你一棵TREE,以及这棵树上边的距离.问有多少对点它们两者间的距离小于等于K Input N(n<=40000) 接下来n-1行边描述管道,按照题目中写的输入 接下来是k Output 一行,有多少对点之间的距离小于等于k Sample Input 7 1 6 13 6…

D Tree Problem Description   There is a skyscraping tree standing on the playground of Nanjing University of Science and Technology. On each branch of the tree is an integer (The tree can be treated as a connected graph with N vertices, while each br…

Tree     Description Give a tree with n vertices,each edge has a length(positive integer less than 1001). Define dist(u,v)=The min distance between node u and v. Give an integer k,for every pair (u,v) of vertices is called valid if and only if dist(u…

Description Give a tree with n vertices,each edge has a length(positive integer less than 1001). Define dist(u,v)=The min distance between node u and v. Give an integer k,for every pair (u,v) of vertices is called valid if and only if dist(u,v) not e…

[CF434E]Furukawa Nagisa's Tree 题意:一棵n个点的树,点有点权.定义$G(a,b)$表示:我们将树上从a走到b经过的点都拿出来,设这些点的点权分别为$z_0,z_1...z_{l-1}$,则$G(a,b)=z_0+z_1k^1+z_2k^2+...+z_{l-1}k^{l-1}$.如果$G(a,b)=X \mod Y$(保证Y是质数),则我们称(a,b)是好的,否则是坏的.现在想知道,有多少个三元组(a,b,c),满足(a,b),(b,c),(a,c)都是好的或者都…

Description Give a tree with n vertices,each edge has a length(positive integer less than 1001). Define dist(u,v)=The min distance between node u and v. Give an integer k,for every pair (u,v) of vertices is called valid if and only if dist(u,v) not e…