1094. The Largest Generation (25)

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.

IDEA

1.树的存储，用的结构vector< vector<int> > tree;

2.树的层序遍历，BFS算法，并且找出每层最大节点数和该层数

3.用到队列，每次外层循环队列大小即为树每层节点数

CODE

#include<iostream>#include<vector>#include<queue>#include<fstream>using namespace std;void BFS(vector<vector<int> >&tree,int &max,int &level,int root){int gen=level,count;queue<int> que;que.push(root);while(!que.empty()){count=que.size();if(count>max){max=count;level=gen;}while(count--){int tmp=que.front();que.pop();vector<int>::iterator it;for(it=tree[tmp].begin();it!=tree[tmp].end();it++){//cout<<(*it)<<" ";que.push(*it);}}gen++;}//cout<<endl<<"gen="<<gen<<endl;}int main(){//freopen("input.txt","r",stdin);int n,m;cin>>n>>m;vector< vector<int> >family;family.resize(n+1);for(int i=0;i<m;i++){int id,k,child;cin>>id>>k;for(int j=0;j<k;j++){cin>>child;//family[id][j]=child;family[id].push_back(child);}}int root=1,level=1,max=1;BFS(family,max,level,root);cout<<max<<" "<<level;//fclose(stdin);return 0;}