这个题目给定一棵树,以及树的每个树枝的苹果数量,要求在保留K个树枝的情况下最多能保留多少个苹果 一看就觉得是个树形DP,然后想出 dp[i][j]来表示第i个节点保留j个树枝的最大苹果数,但是在树形过程中,有点难表示转移 后来看了下大神的做法才知道其实可以用背包来模拟 树枝的去留,其实真的是个背包诶,每个子树枝就相当于物品,他占用了多少树枝量,带来多少的收益,就是用背包嘛,于是用树形DP+背包就可以做了 #include <iostream> #include <cstdio> #…

#include<cstdio> #include<cstring> #include<iostream> #include<algorithm> #include<vector> using namespace std; ; int dp[maxn][maxn]; //dp[i][j]表示以i为根,保留j个点的最大权值. int N,Q; int G[maxn][maxn]; int num[maxn]; //以i为根的树的节点个数. //这里…

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…

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…

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…

组队赛的时候的一道题,那个时候想了一下感觉dp不怎么好写呀,现在写了出来,交上去过了,但是我觉得我还是应该WA的呀,因为总感觉dp的不对. #pragma warning(disable:4996) #include<iostream> #include<cstdio> #include<algorithm> #include<cstring> #include<string> #include<vector> #define max…

题目大意 给定一棵n个结点的树,每个结点上有一定数量的苹果,你可以从结点1开始走k步(从某个结点走到相邻的结点算一步),经过的结点上的苹果都可以吃掉,问你最多能够吃到多少苹果? 题解 蛋疼的问题就是可以往回走~~~~想N就木有想到解法,看了下网上的解题报告~~~~想到了其实还是挺容易理解的~~~分为两种情况,就是有些点只需要走一次,而有些则需要走两次. 方程表示: dp[0][u][j]表示从结点u开始走j步并且返回到结点u获得的最大价值 dp[1][u][j]表示从结点u开始走j步不回到结点u…

#include<cstdio> #include<cstring> #include<algorithm> using namespace std; const int maxn=105; int head[maxn<<1],to[maxn<<1],val[maxn],nex[maxn<<1]; int F[maxn][maxn<<1],G[maxn][maxn<<1]; int cnt,V; void ad…

Let's imagine how apple tree looks in binary computer world. You're right, it looks just like a binary tree, i.e. any biparous branch splits up to exactly two new branches. We will enumerate by integers the root of binary apple tree, points of branch…

Binary Apple Tree Time Limit: 1000ms Memory Limit: 16384KB This problem will be judged on Ural. Original ID: 101864-bit integer IO format: %lld      Java class name: (Any)     Let's imagine how apple tree looks in binary computer world. You're right,…