【bzoj 十连测】[noip2016十连测第二场]Problem C. Dash Speed（树链剖分+并查集）

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
struct tree{
int x,y,t;
}que[140010];
int a[140010],nxt[140010],p[70010],tot;
int f[70010],son[70010],dep[70010],size[70010],top[70010];
int fa[70010],s[70010],t[70010];
int go[1400010],to[1400010],link[1400010],point[262150],tt;
int n,m,cur,ans[70010];
inline void add(int x,int y)
{
tot++; a[tot]=y; nxt[tot]=p[x]; p[x]=tot;
tot++; a[tot]=x; nxt[tot]=p[y]; p[y]=tot;
}
int find(int x)
{
if(fa[x]==x) return x;
fa[x]=find(fa[x]);
}
void dfs(int x,int F,int h)
{
size[x]=1; f[x]=F; dep[x]=h;
for(int i=p[x];i!=-1;i=nxt[i])
if(a[i]!=F)
{
dfs(a[i],x,h+1);
size[x]+=size[a[i]];
if(son[x]==-1||size[son[x]]<size[a[i]]) son[x]=a[i];
}
}
void DFS(int x,int tp)
{
top[x]=tp;
if(son[x]==-1) return;
DFS(son[x],tp);
for(int i=p[x];i!=-1;i=nxt[i])
if(a[i]!=f[x]&&a[i]!=son[x]) DFS(a[i],a[i]);
}

inline int lca(int x,int y)
{
while(top[x]!=top[y])
if(dep[top[x]]<dep[top[y]])
swap(x,y);
if(dep[x]<dep[y]) return x;
return y;
}
inline int dis(int x,int y)
{
return dep[x]+dep[y]-2*dep[lca(x,y)];
}

inline void solve(int x,int y,int &sum)
{
int l1,l2,s1=-1,tmp;
x=find(x); y=find(y);
tmp=dis(S[x],T[x]);
if(tmp>s1) s1=tmp,l1=S[x],l2=T[x];
tmp=dis(S[x],S[y]);
if(tmp>s1) s1=tmp,l1=S[x],l2=S[y];
tmp=dis(S[x],T[y]);
if(tmp>s1) s1=tmp,l1=S[x],l2=T[y];
tmp=dis(T[x],S[y]);
if(tmp>s1) s1=tmp,l1=T[x],l2=S[y];
tmp=dis(T[x],T[y]);
if(tmp>s1) s1=tmp,l1=T[x],l2=T[y];
if(sum<s1) sum=s1;
que[++cur].t=1,que[cur].x=y,que[cur].y=0;
que[++cur].t=2,que[cur].x=x,que[cur].y=S[x];
que[++cur].t=3,que[cur].x=x,que[cur].y=T[x];
fa[y]=x; S[x]=l1; T[y]=l2;
}
inline void pushdown(int now)
{
while(cur>now)
{
if(!que[cur].t) dep[que[cur].x]--;
if(que[cur].t==1) fa[que[cur].x]=que[cur].x;
if(que[cur].t==2) S[que[cur].x]=que[cur].y;
if(que[cur].t==3) T[que[cur].x]=que[cur].y;
cur--;
}
}
void build(int now,int l,int r,int al,int ar,int S,int T)
{
if(al<=l&&r<=ar)
{
tt++;
go[tt]=S,to[tt]=T;
link[tt]=point[S]; point[S]=tt;
return;
}
int mid=(l+r)>>1;
build((now<<1),l,mid,al,ar,S,T);
build((now<<1)|1,mid+1,r,al,ar,S,T);
}
void ask(int now,int l,int r,int sum)
{
int pos=cur;
for(int i=point[now];i!=-1;i=link[i]) solve(S[i],T[i],sum);
if(l==r)
{
ans[l]=sum;
pushdown(pos);
return;
}
int mid=(l+r)>>1;
ask((now<<1),l,mid,sum);
ask((now<<1)|1,mid+1,r,sum);
pushdown(pos);
}
int main()
{
int i;
memset(p,-1,sizeof(p));
memset(nxt,-1,sizeof(nxt));
memset(son,-1,sizeof(son));
memset(link,-1,sizeof(link));
memset(point,-1,sizeof(point));
scanf("%d%d",&n,&m);
for(i=1;i<n;++i)
{
int x,y,al,ar;
scanf("%d%d%d%d",&x,&y,&al,&ar);
add(x,y);
build(1,1,n,al,ar,x,y);
}
dfs(1,0,1);
DFS(1,1);
for(i=1;i<=n;++i) fa[i]=s[i]=t[i]=i;
ask(1,1,n,0);
for(int i=1;i<=m;++i)
{
int x;
scanf("%d",&x);
printf("%d\n",ans[x]);
}
return 0;
}