Apple Tree 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 amount of apples. Wshxzt starts her happy trip at one node. She can eat up all the apple…

题目链接: D - 树形dp  POJ - 2486 题目大意: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 学习网址:https://blog.csdn.net/Aria461863631/article/details/82356420 具体思路: dp[root][j][0]为从root出发,走j步并且最终回到原来点(中间也有可能回到原来的点,但是会继续往下走)的情况下,回到root节点的权值最大值. dp[root][j][1]为从ro…

Apple Tree POJ - 2486 题目大意:一棵点带权有根树,根节点为1.从根节点出发,走k步,求能收集的最大权值和. 树形dp.复杂度可能是O(玄学),不会超过$O(nk^2)$.(反正这题不卡这个,考思想)参考 ans[i][j][0]表示i点以下共走j步,不回来,可能收集到最大的权值ans[i][j][1]表示i点以下共走j步,回来,可能收集到最大的权值 比较复杂的是,每个节点(以下称当前节点)从其子节点转移的时候,需要用一个背包: t[i][j][0]表示当前节点的前i个子节点…

[POJ 2486] Apple Tree(树型dp) Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 8981   Accepted: 2990 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…

E - Apple Tree POJ - 2486 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 amount of apples. Wshxzt starts her happy trip at one node. She can eat up all the ap…

题目链接:http://poj.org/problem?id=2486 思路:经典的树形dp,想了好久的状态转移.dp[i][j][0]表示从i出发走了j步最后没有回到i,dp[i][j][1]表示从i出发走了j步最后回到i.于是我们把所有到情况归结为3种: 1.从u(v是其中一颗子树)出发,走了j步,最后停在了v,则有dp[u][j+1][0]=max(dp[u][j+1][0],dp[u][j-k][1]+dp[v][k][0]);(从u->v多走了1步). 2.从u出发,走了j步,最后停在…

http://poj.org/problem?id=2486 题意: 有n个点,每个点有一个权值,从1出发,走k步,最多能获得多少权值.(每个点只能获得一次) 思路: 从1点开始,往下dfs,对于每个结点,把时间分配给它的子节点,然后求一个最大值. 但是要注意的是,它有可能会走了之后然后又走回到父亲结点,这样的话,状态转移方程需要多考虑一下. d[u][j][0/1]表示从u结点出发走 j 时所能获得的最大权值(0/1表示是否返回u结点). d[u][j][]=max(d[u][j][],d[u…

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: 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 树形DP很弱啊,开始看题,觉得貌似挺简单的,然后发现貌似还可以往回走...然后就不知道怎么做了... 看看了题解http://www.cnblogs.com/wuyiqi/archive/2012/01/09/2316758.html画画题解中的三种情况,还是可以理解的. 设dp[0][s][j]表示从s(当前根节点)出发,走 j 步,回到s所能获得的最大权值 dp[1][s][j]表示从s(当前根节点)出发,走j步,不回到s所能获得的最大权值 现在我们就可以分配背包容量了:父节点与子…