poj 1741

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn=2e4+5;
typedef long long ll;
typedef  unsigned long long ull;
int vis[maxn],n,k,num,d[maxn],_min,tsize[maxn],tssize[maxn],root;
int head[maxn],next[maxn],edge[maxn],val[maxn],tot;
ll ans;
void init(){
    memset(vis,0,sizeof(vis));
    tot=ans=0;
    memset(head,-1,sizeof(head));
}

void addedge(int u,int v,int w){
    edge[tot]=v;
    val[tot]=w;
    next[tot]=head[u];
    head[u]=tot++;
}
//获取子树大小和子树的最大值
void getsize(int u,int f){
    tsize[u]=1;tssize[u]=0;
    for(int i=head[u];i!=-1;i=next[i]){
        int v=edge[i];
        if(v==f||vis[v])continue;
        getsize(v,u);
        tsize[u]+=tsize[v];
        tssize[u]=max(tssize[u],tsize[v]);
    }
}
//重心
void getroot(int r,int u,int f){
    tssize[u]=max(tssize[u],tsize[r]-tsize[u]);
    if(tssize[u]<_min)_min=tssize[u],root=u;
    for(int i=head[u];i!=-1;i=next[i]){
        int v=edge[i];
        if(v==f||vis[v])continue;
        getroot(r,v,u);
    }
}
//求所有点到u的距离
void getdis(int u,int dcnt,int f){
    d[num++]=dcnt;
    for(int i=head[u];i!=-1;i=next[i]){
        int v=edge[i];int w=val[i];
        if(v==f||vis[v])continue;getdis(v,dcnt+w,u);
    }
}

int cal(int u,int dcnt){
    num=0;int ret=0;
    getdis(u,dcnt,-1);
    int i=0,j=num-1;
    sort(d,d+num);
    //for(int i=0;i<num;i++)cout<<d[i]<<" ";cout<<endl;
    while(i<j){
        while(d[i]+d[j]>k&&i<j)j--;
        ret+=j-i;
        i++;
    }
    //cout<<ret<<endl;
    return ret;
}

void dfs(int u){
    _min=n;
    getsize(u,-1);
    getroot(u,u,-1);//cout<<root<<endl;
    ans+=cal(root,0);
    //cout<<root<<"  "<<ans<<endl;
    vis[root]=1;
    int qqq=root;
    for(int i=head[qqq];i!=-1;i=next[i]){
        int v=edge[i],w=val[i];
        if(vis[v])continue;
        ans-=cal(v,w);
        dfs(v);
    }
    //cout<<root<<"  "<<ans<<endl;
}

int main(){
	//freopen("in","r",stdin);
	ios::sync_with_stdio(false);
    while(cin>>n>>k&&n+k){
        init();
        for(int i=0;i<n-1;i++){
            int u,v,w;cin>>u>>v>>w;
            addedge(u,v,w);addedge(v,u,w);
        }
        dfs(1);
        cout<<ans<<endl;
    }
	return 0;
}