[HDU 5293]Tree chain problem(树形dp+树链剖分) 题面 在一棵树中,给出若干条链和链的权值,求选取不相交的链使得权值和最大. 分析 考虑树形dp,dp[x]表示以x为子树的最大权值和(选的链都在i的子树中) 设sum[x]表示x的儿子的dp值和,即\(\sum _{y \in \mathrm{son}(x)} dp[y]\) 1.不选两端点lca为x的链,dp[x]=sum[x] 2.选两端点lca为x的链,则dp[x]=max{链的权值+链上节点的所有子节点dp的…

Problem Description   Coco has a tree, whose vertices are conveniently labeled by 1,2,…,n.There are m chain on the tree, Each chain has a certain weight. Coco would like to pick out some chains any two of which do not share common vertices.Find out t…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5293 题意: 给你一些链,每条链都有自己的价值,求不相交不重合的链能够组成的最大价值. 题解: 树形dp, 对于每条链u,v,w,我们只在lca(u,v)的顶点上处理它 让dp[i]表示以i为根的指数的最大值,sum[i]表示dp[vi]的和(vi为i的儿子们) 则i点有两种决策,一种是不选以i为lca的链,则dp[i]=sum[i]. 另一种是选一条以i为lca的链,那么有转移方程:dp[i]=…

dp dp优化 dfs序 线段树 算是一个套路.可以处理在树上取链的问题.…

树状数组 + dp 设$f_i$表示以$i$为根的子树中的能选取的最大和,$sum_x$表示$\sum_{f_y}$  ($y$是$x$的一个儿子),这样子我们把所有给出的链按照两点的$lca$分组,对于每一个点$x$,$sum_x$显然是一个$f_x$的一个备选答案,而当有树链的$lca$正好是$x$时,我们发现$sum_x + w + \sum_{sum_t} - \sum_{f_t}$($w$代表这条树链能产生的价值,$t$是树链上的一个点). 那么我们只要能快速计算出这两个$\sum$就…

题意: 给出一棵\(n\)个节点的树和\(m\)条链,每条链有一个权值. 从中选出若干条链,两两不相交,并且使得权值之和最大. 分析: 题解 #include <cstdio> #include <cstring> #include <algorithm> #include <map> #include <set> #include <vector> #include <iostream> #include <str…

题目链接 题意: 有n个点的一棵树.其中树上有m条已知的链,每条链有一个权值.从中选出任意个不相交的链使得链的权值和最大. 思路: 树形DP.设dp[i]表示i的子树下的最优权值和,sum[i]表示不考虑i点时子树的最优权值和,即(j是i的儿子),显然dp[i]>=sum[i].那么问题是考虑i点时dp[i]的值是多少,假设有一条链通过i,且端点a和b都在i的子树里,即LCA(a,b)=i,如果考虑加上这条链的权值,那么a->i, b->i的路上的点v都不能有链经过它们(题目要求链不相交…

传送门 题目大意: 一颗n个点的树,给出m条链,第i条链的权值是\(w_i\),可以选择若干条不相交的链,求最大权值和. 题目分析: 树型dp: dp[u][0]表示不经过u节点,其子树的最优值,dp[u][1]表示考虑经过u节点该子树的最优值(可能过,可能不过),很明显:\[dp[u][0] = \sum\{max(dp[v][0], dp[v][1])\} v是u的儿子\], 下面来算dp[u][1]: 考虑一条经过u(以u为lca)的链,他经过子树中的节点v(可能有多个),那么\[dp[u…

[题目] Tree chain problem Problem Description Coco has a tree, whose vertices are conveniently labeled by 1,2,-,n.There are m chain on the tree, Each chain has a certain weight. Coco would like to pick out some chains any two of which do not share comm…

Tree chain problem Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 262    Accepted Submission(s): 59 Problem Description Coco has a tree, whose vertices are conveniently labeled by 1,2,-,n. The…

题目: Problem Description Coco has a tree, whose vertices are conveniently labeled by 1,2,…,n.There are m chain on the tree, Each chain has a certain weight. Coco would like to pick out some chains any two of which do not share common vertices.Find out…

题目:pid=5293">http://acm.hdu.edu.cn/showproblem.php?pid=5293 在一棵树中,给出若干条链和链的权值.求选取不相交的链使得权值和最大. 比赛的时候以为是树链剖分就果断没去想,事实上是没思路. 看了题解,原来是树形dp.话说多校第一场树形dp还真多. . .. 维护d[i],表示以i为根节点的子树的最优答案. sum[i]表示i的儿子节点(仅仅能是儿子节点)的d值和. 那么答案就是d[root]. 怎样更新d值 d[i] = max(su…

问题即:选择价值和最多的链,使得每个点最多被一条链覆盖. 那么考虑其对偶问题:选择最少的点(每个点可以重复选),使得每条链上选了至少$w_i$个点. 那么将链按照LCA的深度从大到小排序,每次若发现点数不够,则在LCA处补充点,树链剖分+线段树维护. 时间复杂度$O(m\log^2n)$. #include<cstdio> #include<algorithm> using namespace std; const int N=100010,M=262150; int Case,c…

HDU 5044 Tree field=problem&key=2014+ACM%2FICPC+Asia+Regional+Shanghai+Online&source=1&searchmode=source" target="_blank" style="">题目链接 就简单的树链剖分,只是坑要加输入外挂,还要手动扩栈 代码: #include <cstdio> #include <cstring>…

Annoying problem 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5293 Description Coco has a tree, whose vertices are conveniently labeled by 1,2,-,n. There are m chain on the tree, Each chain has a certain weight. Coco would like to pick out some ch…

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/* hdu 1402 A * B Problem Plus FFT 这是我的第二道FFT的题 第一题是完全照着别人的代码敲出来的,也不明白是什么意思 这个代码是在前一题的基础上改的 做完这个题,我才有点儿感觉,原来FFT在这里就是加速大整数乘法而已 像前一题,也是一个大整数乘法,然后去掉一些非法的情况 */ #pragma warning(disable : 4786) #pragma comment(linker, "/STACK:102400000,102400000") #in…

HDU 4291 A Short problem(2012 ACM/ICPC Asia Regional Chengdu Online) 题目链接http://acm.hdu.edu.cn/showproblem.php?pid=4291 Description 给一个式子求结果.类似Fibonacci的公式g(n)=3*g(n-1)+g[n-2]. Input 给你n(1<=n<=1e18) Output 求g(g(g(n))) Sample Input 样例第一个就是0什么鬼,虽然没影响.…

题目链接:hdu 2993 MAX Average Problem 题意: 给一个长度为 n 的序列,找出长度 >= k 的平均值最大的连续子序列. 题解: 这题是论文的原题,请参照2004集训队论文<周源--浅谈数形结合思想在信息学竞赛中的应用> 这题输入有点大,要加读入优化才能过. #include<bits/stdc++.h> #define F(i,a,b) for(int i=a;i<=b;++i) using namespace std; int tot;…

题目链接:HDU - 5170GTY's math problem 题目描述 Description GTY is a GodBull who will get an Au in NOI . To have more time to learn algorithm knowledge, he never does his math homework. His math teacher is very unhappy for that, but she can't do anything beca…

hdu 5909 Tree Cutting 题意:一颗无根树,每个点有权值,连通子树的权值为异或和,求异或和为[0,m)的方案数 \(f[i][j]\)表示子树i中经过i的连通子树异或和为j的方案数 转移类似背包,可以用fwt加速 #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> using namespace std; typedef long lon…

hdu 5618 Jam's problem again #include <bits/stdc++.h> #define MAXN 100010 using namespace std; int n,k,T,xx; int ans[MAXN],c[MAXN],f[MAXN]; struct Node{ int x,y,z,id; }a[100010],b[100010]; inline int read(){ char ch; bool f=false; int res=0; while (…

HDOJ(HDU).1016 Prime Ring Problem (DFS) [从零开始DFS(3)] 从零开始DFS HDOJ.1342 Lotto [从零开始DFS(0)] - DFS思想与框架/双重DFS HDOJ.1010 Tempter of the Bone [从零开始DFS(1)] -DFS四向搜索/奇偶剪枝 HDOJ(HDU).1015 Safecracker [从零开始DFS(2)] -DFS四向搜索变种 HDOJ(HDU).1016 Prime Ring Problem (…

数字的反转: 就是将数字倒着存下来而已.(*^__^*) 嘻嘻…… 大致思路:将数字一位一位取出来,存在一个数组里面,然后再将其变成数字,输出. 详见代码. while (a) //将每位数字取出来,取完为止 { num1[i]=a%; //将每一个各位取出存在数组里面,实现了将数字反转 i++; //数组的变化 a/=; } 趁热打铁 例题:hdu 4554 叛逆的小明 题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4554 叛逆的小明 Time…

题目链接: Hdu 5371 Hotaru's problem 题目描述: 给出一个字符串N,要求找出一条N的最长连续子串.这个子串要满足:1:可以平均分成三段,2:第一段和第三段相等,3:第一段和第二段回文. 解题思路: 其实通俗来讲就是求符合题意的最长回文串.先用manacher与处理一下字符串N,得出以n[i]与n[i+1]为中心的回文串长度半径记为p[i],然后循环枚举i作为第一段的终点,p[i]+i-1作为第二段的终点记做j.当p[i]>=(j-i+1)&&p[j]>…

Tree Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 102400/102400 K (Java/Others) Total Submission(s): 1643    Accepted Submission(s): 461 Problem Description   Zero and One are good friends who always have fun with each other. This time, t…

http://acm.hdu.edu.cn/showproblem.php?pid=5475 An easy problem Time Limit: 8000/5000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 755 Accepted Submission(s): 431 Problem Description One day, a useless calculator was…

An easy problem Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5475 Description One day, a useless calculator was being built by Kuros. Let's assume that number X is showed on the screen of calculator. At first,…

An Easy Problem for Elfness Time Limit: 5000/2500 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others)Total Submission(s): 1148    Accepted Submission(s): 234 Problem Description Pfctgeorge is totally a tall rich and handsome guy. He plans t…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=6228 Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 262144/262144 K (Java/Others) Problem DescriptionConsider a un-rooted tree T which is not the biological significance of tree or plant, but a tre…