编程介的小学生 2019-05-20 20:12 采纳率: 20.5%
浏览 165

给一颗二叉树标记颜色的一个算法,怎么使用C语言的程序编写的过程去解决此问题?

Problem Description
Bob is very interested in the data structure of a tree. A tree is a directed graph in which a special node is singled out, called the "root" of the tree, and there is a unique path from the root to each of the other nodes.

Bob intends to color all the nodes of a tree with a pen. A tree has N nodes, these nodes are numbered 1, 2, ..., N. Suppose coloring a node takes 1 unit of time, and after finishing coloring one node, he is allowed to color another. Additionally, he is allowed to color a node only when its father node has been colored. Obviously, Bob is only allowed to color the root in the first try.

Each node has a “coloring cost factor”, Ci. The coloring cost of each node depends both on Ci and the time at which Bob finishes the coloring of this node. At the beginning, the time is set to 0. If the finishing time of coloring node i is Fi, then the coloring cost of node i is Ci * Fi.

For example, a tree with five nodes is shown in Figure-1. The coloring cost factors of each node are 1, 2, 1, 2 and 4. Bob can color the tree in the order 1, 3, 5, 2, 4, with the minimum total coloring cost of 33.

Given a tree and the coloring cost factor of each node, please help Bob to find the minimum possible total coloring cost for coloring all the nodes.

Input
The input consists of several test cases. The first line of each case contains two integers N and R (1 <= N <= 1000, 1 <= R <= N), where N is the number of nodes in the tree and R is the node number of the root node. The second line contains N integers, the i-th of which is Ci (1 <= Ci <= 500), the coloring cost factor of node i. Each of the next N-1 lines contains two space-separated node numbers V1 and V2, which are the endpoints of an edge in the tree, denoting that V1 is the father node of V2. No edge will be listed twice, and all edges will be listed.

A test case of N = 0 and R = 0 indicates the end of input, and should not be processed.

Output
For each test case, output a line containing the minimum total coloring cost required for Bob to color all the nodes.

Sample Input
5 1
1 2 1 2 4
1 2
1 3
2 4
3 5
0 0

Sample Output
33

  • 写回答

0条回答 默认 最新

    报告相同问题?

    悬赏问题

    • ¥15 数学的三元一次方程求解
    • ¥20 iqoo11 如何下载安装工程模式
    • ¥15 本题的答案是不是有问题
    • ¥15 关于#r语言#的问题:(svydesign)为什么在一个大的数据集中抽取了一个小数据集
    • ¥15 C++使用Gunplot
    • ¥15 这个电路是如何实现路灯控制器的,原理是什么,怎么求解灯亮起后熄灭的时间如图?
    • ¥15 matlab数字图像处理频率域滤波
    • ¥15 在abaqus做了二维正交切削模型,给刀具添加了超声振动条件后输出切削力为什么比普通切削增大这么多
    • ¥15 ELGamal和paillier计算效率谁快?
    • ¥15 蓝桥杯单片机第十三届第一场,整点继电器吸合,5s后断开出现了问题