因为上次比赛sb地把一道树形dp当费用流做了,受了点刺激,用一天时间稍微搞一下树形DP,今后再好好搞一下) 基于背包原理的树形DP poj 1947 Rebuilding Roads 题意:给你一棵树,让你求最少剪掉多少条边可以剪出一棵点数为m的子树. 解法:dp[i][j]表示i节点得到j个节点的子树至少要剪多少边,对于每个节点a和它的孩子b,如果剪掉b,则dp(s)[a][j]=dp(s-1)[a][j], 如果保留<a,b>dp(s)[a][j]=min{dp(s-1)[a][j - k…

二叉苹果树 题目 有一棵苹果树,如果树枝有分叉,一定是分2叉(就是说没有只有1个儿子的结点) 这棵树共有N个结点(叶子点或者树枝分叉点),编号为1-N,树根编号一定是1. 我们用一根树枝两端连接的结点的编号来描述一根树枝的位置.下面是一颗有4个树枝的树    2   5     / /      3   4       / /        1 现在这颗树枝条太多了,需要剪枝.但是一些树枝上长有苹果. 给定需要保留的树枝数量,求出最多能留住多少苹果. 输入格式 第1行2个数,N和Q(1<=Q<…

POJ 2342 Anniversary party (树形dp 入门题) Anniversary party Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 4810   Accepted: 2724 Description There is going to be a party to celebrate the 80-th Anniversary of the Ural State University. The U…

Tree chain problem Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1798    Accepted Submission(s): 585 Problem Description Coco has a tree, whose vertices are conveniently labeled by 1,2,…,n.The…

Tree Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1574    Accepted Submission(s): 511 Problem Description In the Data structure class of HEU, the teacher asks one problem: How to find the lon…

Partial Tree http://acm.hdu.edu.cn/showproblem.php?pid=5534 Time Limit: / MS (Java/Others) Memory Limit: / K (Java/Others) Total Submission(s): Accepted Submission(s): Problem Description In mathematics, and more specifically in graph theory, a tree…

Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example, Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3    法I:后序遍历.同Unique Binary Search Trees II,只是现在…

版权声明:本文为博主原创文章,未经博主允许不得转载. Rebuilding Roads Time Limit: 1000MS   Memory Limit: 30000K Total Submissions: 8227   Accepted: 3672 Description The cows have reconstructed Farmer John's farm, with its N barns (1 <= N <= 150, number 1..N) after the terrib…

Easy Tree DP? Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 1460    Accepted Submission(s): 557 Problem Description A Bear tree is a binary tree with such properties : each node has a value o…

题意: 给你一棵树,n个节点,每条边有长度. 然后有q组询问(u,k),每次问你:从节点u出发,走到某个节点的距离mod k的最大值. 题解: 对于无根树上的dp,一般都是先转成以1为根的有根树,然后分别从上到下和从下到上两遍dp. 另一个技巧是:处理重复走边的情况时,可以让dp值表示达到某种状态的方案数. 表示状态: dp[i][j][k] = max dis 表示从i节点出发,走的距离mod k = j时的方案数 找出答案: 对于每次询问(u,k),答案为:满足dp[u][d][k]>0的最…