1094 The Largest Generation (25 分)

bfs,dfs都可以

#include 
#include 
#include 
using namespace std;
vectore[200];
unordered_mapmp,root;
int u,h,s;
void bfs()
{
	queue>que;
	que.push({u,1});
	while(que.size())
	{
        auto t = que.front();que.pop();
		int v = t.first,c = t.second;
		mp[c] ++;
		for(auto it : e[v])
		{
			que.push({it,c + 1});
		}
	}
}
int main()
{
	int n,m;
	cin >> n >> m;
	while(m --)
	{
		int fa,cs,ch;
		cin >> fa >> cs;
		for(int i = 0; i < cs; i ++)
		{
			cin >> ch;
			root[ch] = 1;
			e[fa] .push_back(ch);
		}
	}
	for(int i = 1; i <= n; i ++) if(!root.count(i)) u = i;
	bfs();
	for(auto it : mp)
	{
		if(it.second > s) s = it.second,h = it.first;
	}
	cout << s << ' ' << h << endl;
	return 0;
}