spoj1825 Free tour II（点分治）

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
using namespace std;
#define N 200010
#define ll long long
#define inf 0x3f3f3f3f
#define pa pair<int,int>
inline int read(){
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-'0',ch=getchar();
return x*f;
}
int n,K,m,col
,fa
,sz
,rt,sumsz,g
,mx
,h
,num=0,mxdep;
bool vis
;int dep
,f
,dis
,ans=0;
struct edge{
int to,next,val;
}data[N<<1];
inline void dfs1(int x){
sz[x]=1;
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x]||vis[y]) continue;
fa[y]=x;dep[y]=dep[x]+col[y];dis[y]=dis[x]+data[i].val;

4000
dfs1(y);sz[x]+=sz[y];
}
}
inline void dfs2(int x){
f[x]=0;
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x]||vis[y]) continue;
dfs2(y);f[x]=max(f[x],sz[y]);
}f[x]=max(f[x],sumsz-sz[x]);if(f[x]<f[rt]) rt=x;
}
inline void dfs3(int x){
g[dep[x]]=max(g[dep[x]],dis[x]);
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x]||vis[y]) continue;dfs3(y);
}
}
inline void dfs4(int x){
mxdep=max(mxdep,dep[x]);
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(y==fa[x]||vis[y]) continue;dfs4(y);
}
}
inline void calc(int x){
mx[0]=0;K-=col[x];vector<pa>a;
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(vis[y]) continue;
mxdep=0;dfs4(y);a.push_back(make_pair(mxdep,y));
}sort(a.begin(),a.end());mxdep=0;
for(int ii=0;ii<a.size();++ii){
int y=a[ii].second,now=1;dfs3(y);
for(int i=min(a[ii].first,K);i>=0;--i){
while(now<=mxdep&&now+i<=K) mx[now]=max(mx[now-1],mx[now]),++now;
ans=max(ans,g[i]+mx[now-1]);
}for(int i=0;i<=a[ii].first;++i) mx[i]=max(mx[i],g[i]),g[i]=-inf;
mxdep=a[ii].first;
}K+=col[x];
for(int i=0;i<=mxdep;++i) mx[i]=g[i]=-inf;
}
inline void solve(int x){
vis[x]=1;fa[x]=0;dep[x]=0;dis[x]=0;dfs1(x);calc(x);
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(vis[y]) continue;
rt=0;sumsz=sz[y];dfs2(y);solve(rt);
}
}
int main(){
//  freopen("a.in","r",stdin);
n=read();K=read();m=read();f[0]=inf;
for(int i=1;i<=m;++i) col[read()]=1;
for(int i=0;i<=K;++i) mx[i]=g[i]=-inf;
for(int i=1;i<n;++i){
int x=read(),y=read(),val=read();
data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=val;
data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=val;
}dfs1(1);rt=0;sumsz=n;dfs2(1);solve(rt);
printf("%d\n",ans);
return 0;
}