• A


    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 branching and the ends of twigs. This way we may distinguish different branches by their ending points. We will assume that root of tree always is numbered by 1 and all numbers used for enumerating are numbered in range from 1 to N, where N is the total number of all enumerated points. For instance in the picture below N is equal to 5. Here is an example of an enumerated tree with four branches:
    2   5
      / 
      3   4
        /
        1
    
    As you may know it's not convenient to pick an apples from a tree when there are too much of branches. That's why some of them should be removed from a tree. But you are interested in removing branches in the way of minimal loss of apples. So your are given amounts of apples on a branches and amount of branches that should be preserved. Your task is to determine how many apples can remain on a tree after removing of excessive branches.

    Input

    First line of input contains two numbers: N and Q ( 2 ≤ N ≤ 100; 1 ≤ Q ≤ N − 1 ). N denotes the number of enumerated points in a tree. Q denotes amount of branches that should be preserved. Next N − 1 lines contains descriptions of branches. Each description consists of a three integer numbers divided by spaces. The first two of them define branch by it's ending points. The third number defines the number of apples on this branch. You may assume that no branch contains more than 30000 apples.

    Output

    Output should contain the only number — amount of apples that can be preserved. And don't forget to preserve tree's root ;-)

    Example

    inputoutput
    5 2
    1 3 1
    1 4 10
    2 3 20
    3 5 20
    
    21
    #include<bits/stdc++.h>
    using namespace std;
    vector<int>g[105];
    int num[105][105],cnt[105];
    int dp[105][105];
    int n,q;
    bool vis[105];
    
    void getcnt(int u)
    {
        vis[u]=true;
        cnt[u]=0;
        for(int i=0;i<g[u].size();i++)
        {
            int v=g[u][i];
            if(!vis[v])
            {
                cnt[u]++;
                getcnt(v);
                cnt[u]+=cnt[v];
            }
        }
    }
    
    void dfs(int u)
    {
        vis[u]=true;
        int first=0,second=0;
        for(int i=0;i<g[u].size();i++)
        {
            int v=g[u][i];
            if(!vis[v])
            {
                if(first)
                  second=v;
                else
                  first=v;
                dfs(v);
            }
        }
        if(second)
        {
            for(int i=1;i<n;i++)
            {
                if(i>cnt[u])
                {
                    dp[u][i]=-1;
                    continue;
                }
                dp[u][i]=0;
                if(cnt[first]>=i-1)
                {
                    dp[u][i]=max(dp[u][i],num[u][first]+dp[first][i-1]);
                }
                if(cnt[second]>=i-1)
                {
                    dp[u][i]=max(dp[u][i],num[u][second]+dp[second][i-1]);
                }
                int tmp=num[u][first]+num[u][second];
                for(int j=0;j<=i-2;j++)
                {
                    if(cnt[first]>=j&&cnt[second]>=i-2-j)
                      dp[u][i]=max(dp[u][i],tmp+dp[first][j]+dp[second][i-2-j]);
                      
                }
            }
        }
        else if(first)
        {
            for(int i=1;i<n;i++)
            {
                if(i>cnt[u])
                {
                    dp[u][i]=-1;
                    continue;
                }
                if(cnt[first]>=i-1)
                {
                    dp[u][i]=num[u][first]+dp[first][i-1];
                }
            }
        }
        else
        {
            for(int i=1;i<n;i++)
              dp[u][i]=-1;
        }
    }
    
    int main()
    {
        cin>>n>>q;
        for(int i=1;i<n;i++)
        {
            int u,v,c;
            cin>>u>>v>>c;
            g[u].push_back(v);
            g[v].push_back(u);
            num[u][v]=num[v][u]=c;
        }
        memset(vis,false,sizeof(vis));
        getcnt(1);
        memset(vis,false,sizeof(vis));
        dfs(1);
        cout<<dp[1][q]<<"
    ";
        return 0;
    }
  • 相关阅读:
    tableView滑动时cell消失
    收集别人写的很好的关于多线程的文章
    scroll或是其子类被添加进view时,界面自动上移
    runtime之实现对象序列化
    runtime之方法的交换
    升级mac中的系统之后,给PHP安装扩展常出现问题
    ubuntu下搭建Scrapy框架简单办法
    CuDA的快速下载链接
    windows下Scrapy爬虫框架环境搭建
    windows下安装pywin32报错:close failed in file object destructor:sys.excepthook is missing lost sys.stderr
  • 原文地址:https://www.cnblogs.com/ylrwj/p/11960157.html
Copyright © 2020-2023  润新知