Uva 网络(Network,Seoul 2007,LA 3902)

#include<iostream>
#include<cstring>
#include<vector>
using namespace std;

const int maxn=1000+10;
int n,s,k;
vector<int> tree[maxn],nodes[maxn];
int fa[maxn];
bool covered[maxn];

void dfs(int u,int f,int d)
{
    fa[u]=f;
    int nc=tree[u].size();
    if(nc==1&&d>k) nodes[d].push_back(u);
    for(int i=0;i<nc;i++)
        if(tree[u][i]!=f) dfs(tree[u][i],u,d+1);
}

void dfs2(int u,int f,int d)
{
    int nc=tree[u].size();
    covered[u]=true;
    for(int i=0;i<nc;i++)
        if(tree[u][i]!=f&&d<k)
            dfs2(tree[u][i],u,d+1);
}

int solve()
{
    int ans=0;
    memset(covered,0,sizeof(covered));
    for(int d=n-1;d>k;d--)
        for(int i=0;i<nodes[d].size();i++)
        {
            int u=nodes[d][i];
            if(covered[u]) continue;
            int v=u;
            for(int j=0;j<k;j++) v=fa[v];
            dfs2(v,-1,0);
            ans++;
        }
    return ans;
}

int main()
{
    int T;
    cin>>T;
    while(T--)
    {
        cin>>n>>s>>k;
        for(int i=1;i<=n;i++)
        {
            tree[i].clear();
            nodes[i].clear();
        }
        for(int i=1;i<=n-1;i++)
        {
            int a,b;
            cin>>a>>b;
            tree[a].push_back(b);
            tree[b].push_back(a);
        }
        dfs(s,-1,0);
        cout<<solve()<<endl;
    }
    return 0;
}