http://poj.org/problem?id=2486 典型的回溯题目:特别是状态方程用三维的来标记是否要走回路. 题意:一颗树,n个点(1-n),n-1条边,每个点上有一个权值,求从1出发,走V步,最多能遍历到的权值 思路: 树形dp,比较经典的一个树形dp.首先很容易就可以想到用dp[root][k]表示以root为根的子树中最多走k时所能获得的最多苹果数,接下去我们很习惯地会想到将k步在root的所有子结点中分配,也就是进行一次背包,就可以得出此时状态的最优解了,但是这里还有一个问题…

POJ.3321 Apple Tree ( DFS序 线段树 单点更新 区间求和) 题意分析 卡卡屋前有一株苹果树,每年秋天,树上长了许多苹果.卡卡很喜欢苹果.树上有N个节点,卡卡给他们编号1到N,根的编号永远是1.每个节点上最多结一个苹果.卡卡想要了解某一个子树上一共结了多少苹果. 现在的问题是不断会有新的苹果长出来,卡卡也随时可能摘掉一个苹果吃掉.你能帮助卡卡吗? 前缀技能 边表存储树 DFS时间戳 线段树 首先利用边表将树存储下来,然后DFS打上时间戳.打上时间戳之后,我们就知道书上节点对…

id=10486" target="_blank" style="color:blue; text-decoration:none">POJ - 3321 Apple Tree Time Limit: 2000MS   Memory Limit: 65536KB   64bit IO Format: %I64d & %I64u Submit Status Description There is an apple tree outside o…

好抽象的树形DP......... Apple Tree Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 6411 Accepted: 2097 Description Wshxzt is a lovely girl. She likes apple very much. One day HX takes her to an apple tree. There are N nodes in the tree. Each nod…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 18623   Accepted: 5629 Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K       Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been carefully nurturing the big apple t…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 25904   Accepted: 7682 Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been…

Apple Tree Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 9808   Accepted: 3260 Description Wshxzt is a lovely girl. She likes apple very much. One day HX takes her to an apple tree. There are N nodes in the tree. Each node has an amoun…

题目链接:http://poj.org/problem?id=3321 Apple Tree Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 34812 Accepted: 10469 Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka like…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 25232   Accepted: 7503 Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been…