1094. The Largest Generation (25)-PAT甲级真题(bfs,dfs,树的遍历)

A family hierarchy is usually presented by a pedigree tree where all the nodes on the same level belong to the same generation. Your task is to find the generation with the largest population.

Input Specification:

Each input file contains one test case. Each case starts with two positive integers N (<100) which is the total number of family members in the tree (and hence assume that all the members are numbered from 01 to N), and M (<N) which is the number of family members who have children. Then M lines follow, each contains the information of a family member in the following format:

ID K ID[1] ID[2] … ID[K]

where ID is a two-digit number representing a family member, K (>0) is the number of his/her children, followed by a sequence of two-digit ID’s of his/her children. For the sake of simplicity, let us fix the root ID to be 01. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print in one line the largest population number and the level of the corresponding generation. It is assumed that such a generation is unique, and the root level is defined to be 1.

Sample Input:
23 13
21 1 23
01 4 03 02 04 05
03 3 06 07 08
06 2 12 13
13 1 21
08 2 15 16
02 2 09 10
11 2 19 20
17 1 22
05 1 11
07 1 14
09 1 17
10 1 18
Sample Output:
9 4
题目大意:输入树的结点个数N,结点编号为1~N,非叶子结点个数M,然后输出M个非叶子结点格子的孩子结点的编号,求结点个数最多的一层,根结点的层号为1,输出该层的结点个数以及层号<(▰˘◡˘▰)>
分析:用DFS或者BFS,用DFS就用参数index和level标记当前遍历的结点的编号和层数,一个数组book标记当前层数level所含结点数,最后遍历一遍数组找出最大值。注意 :book[level]++;这句话是发生在return语句判断之前的外面,即每遇到一个结点都要进行处理,而不是放在return语句的条件判断里面~~
如果是BFS,就用一个数组level[i]标记i结点所处的层数,它等于它的父亲结点的level的值+1,用一个数组book,book[i]标记i层所拥有的结点数,在遍历的时候每弹出一个结点就将当前结点的层数所对应的book值+1,最后遍历一遍book数组找出最大拥有的结点数和层数~

  • 深度优先dfs方法:

  • 广度优先bfs方法: