Find Metal Mineral Problem Description Humans have discovered a kind of new metal mineral on Mars which are distributed in point‐like with paths connecting each of them which formed a tree. Now Humans launches k robots on Mars to collect them, and du…

题意:给出n个点的一棵树,有k个机器人,机器人从根节点rt出发,问访问完整棵树(每个点至少访问一次)的最小代价(即所有机器人路程总和),机器人可以在任何点停下. 解法:这道题还是比较明显的能看出来是树形DP,然后分配机器人肯定想到树形分组背包DP.那么dp方程和常规树形背包dp一样很容易些 dp[x][i]=min(dp[x][i],dp[y][j]+val(y,j)+dp[x][i-j]) 代表总共i个机器人给当前子树y分配j个机器人剩下的i-j个机器人分配给前几棵子树的最小代价.主要问题就是…

Find Metal Mineral Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65768/65768 K (Java/Others)Total Submission(s): 3397    Accepted Submission(s): 1588 Problem Description Humans have discovered a kind of new metal mineral on Mars which are d…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4003 Humans have discovered a kind of new metal mineral on Mars which are distributed in point‐like with paths connecting each of them which formed a tree. Now Humans launches k robots on Mars to collect…

Find Metal Mineral Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65768/65768 K (Java/Others) Total Submission(s): 2018    Accepted Submission(s): 913 Problem Description Humans have discovered a kind of new metal mineral on Mars which are d…

4003 思维啊 dp[i][j]表示当前I节点停留了j个机器人 那么它与父亲的关系就有了 那条边就走了j遍 dp[i][j] = min(dp[i][j],dp[child][g]+dp[i][j-g]+g*w[i][child] ); #include <iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<stdlib.h> #include<…

看别人思路的 树形分组背包. 题意:给出结点数n,起点s,机器人数k,然后n-1行给出相互连接的两个点,还有这条路线的价值,要求最小花费 思路:这是我从别人博客里找到的解释,因为很详细就引用了 dp[i][j]表示对于以i结点为根结点的子树,放j个机器人所需要的权值和. 当j=0时表示放了一个机器人下去,遍历完结点后又回到i结点了.状态转移方程类似背包 如果最终的状态中以i为根结点的树中有j(j>0)个机器人,那么不可能有别的机器人r到了这棵树后又跑到别的树中去 因为那样的话,一定会比j中的某一…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4003 Find Metal Mineral Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65768/65768 K (Java/Others)Total Submission(s): 4490    Accepted Submission(s): 2071 Problem Description Humans have discov…

题目大意:用m个机器人去遍历有n个节点的有根树,边权代表一个机器人通过这条边的代价,求最小代价. 题目分析:定义状态dp(root,k)表示最终遍历完成后以root为根节点的子树中有k个机器人时产生的总代价.则状态转移方程为: dp(root,k)=min(dp(root,k),dp(son,j)+dp(root,k-j)+j*w(root,son))  j>0 要注意,当j为0的时候表示遍历完son这个子树后所有的机器人都回到root.可以证明,如果让遍历son的所有的机器人都回到root,那…

[HDU4003]Find Metal Mineral Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65768/65768 K (Java/Others)Total Submission(s): 3686    Accepted Submission(s): 1723 Problem Description Humans have discovered a kind of new metal mineral on Mars wh…