树状dp Anniversary party

ゞ浴缸里的玫瑰 2022-06-17 20:14 159阅读 0赞

#include<cstdio>
    #include<cstring>
    #include<algorithm>
    #include<vector>
    #include <iostream>
    using namespace std;
    const int MAXN=6005;
    vector<int> tree[MAXN];   
    int n,r,maxn;
    int value[MAXN];
    int root[MAXN];
    int dp[MAXN][2];  //dp[i][0]代表第i个人不来  dp[i][1]代表这个人来的最大欢乐值 
    void dfs(int u)   //从最顶层的上司向下遍历 
    {
    	
    	for(int i=0;i<tree[u].size();i++)   
    	{
    		int v=tree[u][i];
    		dfs(v);      
    		dp[u][1]+=dp[v][0];  //根节点的人来，那么他的叶子们不来  
    	    dp[u][0]+=max(dp[v][1],dp[v][0]); //根节点的人不来，那么他的叶子们来或者不来 ，在其中找到最大的值 
    	}
    
    
    }
    int main()
    {
    	
        while(scanf("%d",&n) !=EOF)
        {
        	memset(root,0,sizeof(root));
            memset(dp,0,sizeof(dp));
            memset(value,0,sizeof(value));
            for(int i=1;i<=n;i++) 
            tree[i].clear();
        
    	    for(int i=1;i<=n;i++)
    	       {
    	       	scanf("%d",&value[i]);
    	       	dp[i][1]=value[i];
    	       } 
    	    int L,K;
    	    while(scanf("%d %d",&L,&K) && (L+K))  
    	    {
    	        root[L]=1;
    	        tree[K].push_back(L);
    
    	    }
    	    for(int i=1;i<=n;i++)  //找到最顶层的上司 
    	    {
    	    	if(root[i]==0) 
    			{
    		    	r=i;
    		    	break;
    	        }
    	    }
    	
    	    dfs(r);
    	    maxn=max(dp[r][0],dp[r][1]);
    	    printf("%d\n",maxn);
    	 }
        return 0;
    }

There is going to be a party to celebrate the 80-th Anniversary of the Ural State University. The University has a hierarchical structure of employees. It means that the supervisor relation forms a tree rooted at the rector V. E. Tretyakov. In order to make the party funny for every one, the rector does not want both an employee and his or her immediate supervisor to be present. The personnel office has evaluated conviviality of each employee, so everyone has some number (rating) attached to him or her. Your task is to make a list of guests with the maximal possible sum of guests' conviviality ratings.  
  
Input  
  
  
Employees are numbered from 1 to N. A first line of input contains a number N. 1 <= N <= 6 000. Each of the subsequent N lines contains the conviviality rating of the corresponding employee. Conviviality rating is an integer number in a range from -128 to 127. After that go N – 1 lines that describe a supervisor relation tree. Each line of the tree specification has the form:  
L K  
It means that the K-th employee is an immediate supervisor of the L-th employee. Input is ended with the line  
0 0  
  
  
Output  
  
  
Output should contain the maximal sum of guests' ratings.  
  
Sample Input  
  
7  
1  
1  
1  
1  
1  
1  
1  
1 3  
2 3  
6 4  
7 4  
4 5  
3 5  
0 0  
  
  
Sample Output  
  
5