1004. Counting Leaves (30)

考察树结构的简单存储以及遍历搜索

#include <iostream>
#include <vector>
#include <queue>

int n, m;
std::vector<std::vector<int>> edge;
std::vector<int> BFS(int s)
{
	std::queue<std::pair<int,int>> q;
	q.push(std::make_pair(s, 0));
	int cur_step = 0;
	std::vector<int> ans;
	int cnt = 0;
	while (!q.empty())
	{
		int u = q.front().first;
		int step = q.front().second;
		q.pop();
		if(step > cur_step)
		{
			ans.push_back(cnt);
			cnt = 0;
			cur_step = step;
		}
		if(edge[u].size() == 0) cnt++;
		for (int i = 0; i < edge[u].size(); ++i)
		{
			int v = edge[u][i];
			q.push(std::make_pair(v, step+1));
		}
	}
	ans.push_back(cnt);
	return ans;
}
int main()
{
	while (scanf("%d%d",&n,&m)!=EOF)
	{
		//input edges
		edge.clear();
		edge.resize(n+1);
		while (m--)
		{
			int a, k;
			scanf("%d%d", &a,&k);
			while (k--)
			{
				int b;
				scanf("%d",&b);
				edge[a].push_back(b);
				//edge[b].push_back(a);
			}
		}
		std::vector<int> ans = BFS(1);
		//output
		for (int i = 0; i < ans.size(); ++i)
		{
			if(i != ans.size()-1)
				printf("%d ", ans[i]);
			else printf("%d\n", ans[i]);
		}
	}
	return  0;
}