hdu5534 Partial Tree

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)
Total Submission(s): 126    Accepted Submission(s): 68

Problem Description

In mathematics, and more specifically in graph theory, a tree is an undirected graph in which any two nodes are connected by exactly one path. In other words, any connected graph without simple cycles is a tree.

You find a partial tree on the way home. This tree has  n  nodes but lacks of  n−1  edges. You want to complete this tree by adding  n−1  edges. There must be exactly one path between any two nodes after adding. As you know, there are  nn−2  ways to complete this tree, and you want to make the completed tree as cool as possible. The coolness of a tree is the sum of coolness of its nodes. The coolness of a node is  f(d) , where  f  is a predefined function and  d  is the degree of this node. What's the maximum coolness of the completed tree?

 

Input

The first line contains an integer  T  indicating the total number of test cases.
Each test case starts with an integer  n  in one line,
then one line with  n−1  integers  f(1),f(2),…,f(n−1) .

1≤T≤2015
2≤n≤2015
0≤f(i)≤10000
There are at most  10  test cases with  n>100 .

 

Output

For each test case, please output the maximum coolness of the completed tree in one line.

 

Sample Input

   
   
   
   

    
    
    
    2
3
2 1
4
5 1 4
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    5
19
   
   
   
   

 

注意到一个节点数为n的树的度数和玮2*n-2,所以问题就转换为了把2*n-2个度分配给n个节点所能获得的最大价值，而且每一个节点至少分到1个度。我们可以先每一个分一个度，然后把n-2个节点任意分配完。分配的时候因为已经分了1个度了，所以要把2~n-1的度看为1~n-1，然后做个完全背包就行了。

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<string>
#include<algorithm>
using namespace std;
typedef long long ll;
#define inf 99999999
int v[2200],dp[2200];
int main()
{
    int n,m,i,j,T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(i=1;i<=n-1;i++){
            scanf("%d",&v[i]);
        }
        int ans=0;
        ans+=v[1]*n;
        for(i=2;i<=n-1;i++){
            v[i]-=v[1];
        }
        for(i=1;i<=n-2;i++){
            dp[i]=-inf;
        }
        dp[0]=0;
        for(i=1;i<=n-2;i++){
            v[i]=v[i+1];
        }
        for(i=1;i<=n-2;i++){
            for(j=i;j<=n-2;j++){
                dp[j]=max(dp[j],dp[j-i]+v[i]);
            }
        }
        ans+=dp[n-2];
        printf("%d\n",ans);
    }
}