A1094 The Largest Generation (25 point(s))

BFS统计层结点数

1. 原文

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

2. 解析

层序遍历结点level[deep]++;

3. AC代码

#include<cstdio>
#include<vector>
#include<queue>
using namespace std;
vector<int> v[110];
int deep=1;
int level[110]={};
void bfs(int root){
	queue<int> q;
	q.push(root);
	int lastnode=root;
	int nownode=0;
	while(!q.empty()){
		int temp=q.front();
		//printf("%d\n",temp);
		level[deep]++;
		q.pop();
		for (int i = 0; i < v[temp].size(); ++i)
		{
			q.push(v[temp][i]);
			nownode=v[temp][i];
		}
		if (lastnode==temp)
		{
			deep++;
			lastnode=nownode;
		}
	}
}
int main()
{
	int n,m;
	scanf("%d%d",&n,&m);
	for (int i = 0; i < m; ++i)
	{
		int id,k,a;
		scanf("%d%d",&id,&k);
		for (int j = 0; j < k; ++j)
		{
			scanf("%d",&a);
			v[id].push_back(a);
		}
	}
	bfs(1);
	int maxnum=-1; int maxidx=0;
	for (int i = 1; i <= deep; ++i)
	{
		int size=level[i];
		if (size>maxnum)
		{
			maxnum=size;
			maxidx=i;
		}
		
	}
	printf("%d %d\n",maxnum,maxidx);
	return 0;
}