hdu 4707 bfs

bfs基础算法水题

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>

using namespace std;

const int Max = 1e5+50;

int dist[Max];
vector<int> tree[Max];

int N, D, T;

void init()
{
	for(int i = 0; i < Max-40; i ++)
	{
		tree[i].clear();
	}
	memset(dist, 0, sizeof(dist));
}

int ans;
void bfs()
{
	int t = 0, dis = 0;
	queue<int> q;
	q.push(t);
	ans ++;
	while(!q.empty())
	{
		t = q.front();
		q.pop();
		if(dist[t] + 1 > D) continue;
		for(int i = 0; i < tree[t].size(); i ++)
		{
			dist[tree[t][i]] = dist[t] + 1;
			ans ++;
			q.push(tree[t][i]);
		}
	}
}

int main()
{
	int x, y;

	scanf("%d", &T);
	while(T --)
	{
		init();
		scanf("%d%d", &N, &D);
		for(int i = 0; i < N-1; i ++)
		{
			scanf("%d%d", &x, &y);
			tree[x].push_back(y);
		}
		ans = 0;
		bfs();
		printf("%d\n", N-ans);
	}

	return 0;
} 

hdu 4707 bfs