Gardener and Tree
题意:k次操作,每次删去叶子节点,问最后剩的节点
思路:拓扑,度为1的就是叶子结点
//#pragma GCC optimize(2)
//#pragma GCC optimize(3,"Ofast","inline")
#include<bits/stdc++.h>
#define int long long
#define fi first
#define se second
#define pb push_back
#define pii pair<int,int>
#define IOS ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
const int inf=2e18+100;
const int maxn=4e5+100;
vector<int>g[maxn];
int in[maxn];
bool vis[maxn];
signed main()
{
IOS
int tt;
cin>>tt;
while(tt--)
{
queue<pii>q;
int n,k;
cin>>n>>k;
memset(vis,0,sizeof(bool)*(n+10));
memset(in,0,sizeof(int)*(n+10));
for(int i=1;i<=n;i++)g[i].clear();
for(int i=1;i<n;i++)
{
int u,v;
cin>>u>>v;
g[u].pb(v);
g[v].pb(u);
in[u]++;
in[v]++;
}
if(n==1)
{
if(k>=1)cout<<"0"<<"\n";
else cout<<"1"<<"\n";
continue;
}
for(int i=1;i<=n;i++)
{
if(in[i]==1)
{
q.push({i,1});
vis[i]=1;
}
}
while(!q.empty())
{
auto now=q.front();
if(now.se>k)break;
vis[now.fi]=1;
q.pop();
for(auto it:g[now.fi])
{
in[it]--;
if(in[it]==1)
{
if(now.se+1<=k)
{
q.push({it,now.se+1});
}
}
}
}
int ans=0;
for(int i=1;i<=n;i++)
{
if(!vis[i])ans++;
}
cout<<ans<<"\n";
}
}