poj1741(点分模板)

#include<iostream>
#include<cstring>
#include<cmath>
#include<cstdio>
#include<algorithm>
using namespace std;
const int maxn=10010;
int last[maxn],pre[maxn*2],other[maxn*2],w[maxn*2],t,vis[maxn];
void add(int x,int y,int z){++t;pre[t]=last[x];last[x]=t;other[t]=y;w[t]=z;}
int cnt,root,d[maxn],siz[maxn],f[maxn],sizz,q[maxn];
int x,y,z,n,m,k,ans;
void getroot(int x,int fa){
    siz[x]=1;f[x]=0;
    for(int i=last[x];i;i=pre[i]){
        int v=other[i];
        if(v==fa||vis[v])continue;
        getroot(v,x);
        siz[x]+=siz[v];
        f[x]=max(f[x],siz[v]);
    }
    f[x]=max(f[x],sizz-siz[x]);
    if(f[x]<f[root])root=x;
}
void getdis(int x,int fa){
    q[++cnt]=d[x];
    for(int i=last[x];i;i=pre[i]){
        int v=other[i];
        if(v==fa||vis[v])continue;
        d[v]=d[x]+w[i];
        getdis(v,x);
    }
}
int calc(int x,int init){
    cnt=0;d[x]=init;
    getdis(x,0);
    sort(q+1,q+cnt+1);
    int res=0;
    for(int l=1,r=cnt;l<r;){
        if(q[l]+q[r]<=k){res+=r-l;l++;}
        else r--;
    }
    return res;
}
void solve(int x){
    ans+=calc(x,0);
    vis[x]=1;
    for(int i=last[x];i;i=pre[i]){
        int v=other[i];
        if(vis[v])continue;
        ans-=calc(v,w[i]);
        f[0]=sizz=siz[v];
        root=0;
        getroot(v,0);
        solve(root);
    }
}
int main(){
    while(scanf("%d%d",&n,&k)!=EOF){
        if(n==0&&k==0)break;
        memset(last,0,sizeof(last));
        memset(vis,0,sizeof(vis));
        t=0;
        for(int i=1;i<n;++i){
            scanf("%d%d%d",&x,&y,&z);
            add(x,y,z);add(y,x,z);
        }
        f[0]=sizz=n;ans=root=0;
        getroot(1,0);
        solve(root);
        printf("%d
",ans);
    }
    return 0;
}