POJ2342Anniversary party题解动态规划DP

最新推荐文章于 2016-12-30 12:43:00 发布

原创最新推荐文章于 2016-12-30 12:43:00 发布 · 759 阅读

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#input #structure #each #integer #tree #forms

本文介绍了一道关于大学校庆派对的算法题目，旨在通过员工邀请名单的优化来实现最大化的欢乐指数。文章详细阐述了问题背景、输入输出格式及样例，并给出了基于树形动态规划的解决方案。

Anniversary party

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 1507		Accepted: 782

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

Sample Output

Source

Ural State University Internal Contest October'2000 Students Session

和POj1463类似的树型DP

状态：

d[i][0]表示不选i结点的最大值

d[i][1]表示选i结点的最大值

状态转移方程：

j是i的儿子结点

d[i][0]=sum{max(d[j][0],d[j][1])}

d[i][1]=sum{d[j][0]}

边界：

d[i][1]=a[i]

代码：