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1463：Strategic game

题目描述
Bob enjoys playing computer games, especially strategic games, but sometimes he cannot find the solution fast enough and then he is very sad. Now he has the following problem. He must defend a medieval city, the roads of which form a tree. He has to put the minimum number of soldiers on the nodes so that they can observe all the edges. Can you help him?

Your program should find the minimum number of soldiers that Bob has to put for a given tree.

For example for the tree:

the solution is one soldier ( at the node 1).
输入解释
The input contains several data sets in text format. Each data set represents a tree with the following description:

  • the number of nodes
  • the description of each node in the following format
    node_identifier:(number_of_roads) node_identifier1 node_identifier2 ... node_identifiernumber_of_roads
    or
    node_identifier:(0)

The node identifiers are integer numbers between 0 and n-1, for n nodes (0 < n <= 1500);the number_of_roads in each line of input will no more than 10. Every edge appears only once in the input data.
输出解释
The output should be printed on the standard output. For each given input data set, print one integer number in a single line that gives the result (the minimum number of soldiers). An example is given in the following:
输入样例 
4
0:(1) 1
1:(2) 2 3
2:(0)
3:(0)
5
3:(3) 1 4 2
1:(1) 0
2:(0)
0:(0)
4:(0)
输出样例 
1
2
该题目是Virtual Judge题目，来自 北京大学POJ
题目来源 Southeastern Europe 2000
源链接： POJ-1463
最后修改于 2020-10-29T06:04:50+00:00 由爬虫自动更新
共提交 0 次
通过率 --%
时间上限 内存上限
2000 10000