poj 2342(树型dp)

Anniversary party

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 7169 Accepted: 4135

Description

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

711111111 32 36 47 44 53 50 0

Sample Output

5

题意：

每个人有一个宴会值，有一个树型的职位关系图，每个人不能和自己的直系上司参加宴会，最后求出办一场宴会的最大宴会值。

思路：

把职位关系建成一棵树，记录每个人的直系上司。

每个人的dp数组为dp[n][2]。dp[i][0]代表这个人不出席，dp[i][1]代表这个人出席。

递推公式为：

dp[i][0]=max(dp[j][1],dp[j][0])

dp[i][1]=dp[j][0]

#include<stdio.h>#include<iostream>#include<algorithm>#include<string.h>#include<vector>#include<bitset>#include<queue>#include<stack>#include<list>#include<set>#include<math.h>#include<map>using namespace std;int n,m,dp[6005][2],fa[6005],vis[6005];void treedp(int node){    vis[node]=1;    for(int i=1;i<=n;i++)    {        if(!vis[i]&&fa[i]==node)        {            treedp(i);            dp[node][0]+=max(dp[i][1],dp[i][0]);            dp[node][1]+=dp[i][0];        }    }}int main(){freopen("in.txt","r",stdin);//freopen("out.txt","w",stdout);scanf("%d",&n);memset(dp,0,sizeof(dp));memset(fa,0,sizeof(fa));memset(vis,0,sizeof(vis));for(int i=1;i<=n;i++)    {        scanf("%d",&dp[i][1]);    }    int u,v;    while(scanf("%d%d",&u,&v))    {        if(u==0&&v==0)            break;        fa[u]=v;    }    int root=1;    while(fa[root])        root=fa[root];    treedp(root);    printf("%d\n",max(dp[root][1],dp[root][0]));return 0;}