比较快也比较漂亮的熟练剖分模板（BZOJ 1036：树剖+线段树 BZOJ 1103：树剖+树状数组）

#include<bits/stdc++.h>
#define N 100005
#define inf 1000000000
using namespace std;
int n,q,a[4*N];
struct Edge{
int u,v,next;
}G
;
int tot=0,head
;
int size[100005],wson[100005],fa[100005],d[100005],top[100005];
int tpos[100005],pre[100005],cnt=0;
inline void addedge(int u,int v){
G[++tot].u=u;G[tot].v=v;G[tot].next=head[u];head[u]=tot;
G[++tot].u=v;G[tot].v=u;G[tot].next=head[v];head[v]=tot;
}
void dfs1(int u,int f){
size[u]=1;
for (int i=head[u];i;i=G[i].next){
int v=G[i].v;if (v==f)continue;
d[v]=d[u]+1;fa[v]=u;
dfs1(v,u);
size[u]+=size[v];
if (size[v]>size[wson[u]])wson[u]=v;
}
}
void dfs2(int u,int TP){
tpos[u]=++cnt;pre[cnt]=u;top[u]=TP;
if (wson[u])dfs2(wson[u],TP);
for (int i=head[u];i;i=G[i].next){
int v=G[i].v;
if (v==fa[u]||v==wson[u])continue;
dfs2(v,v);
}
}
int sumv[4*N],maxv[4*N];
inline void pushup(int o){
sumv[o]=sumv[o*2]+sumv[o*2+1];
maxv[o]=max(maxv[o*2],maxv[o*2+1]);
}
void build(int o,int l,int r){
int mid=(l+r)/2;
if (l==r){sumv[o]=maxv[o]=a[pre[l]];return;}
build(o*2,l,mid);build(o*2+1,mid+1,r);
pushup(o);
}
void update(int o,int l,int r,int q,int v){
int mid=(l+r)/2;
if (l==r){sumv[o]=maxv[o]=v;return;}
if (q<=mid)update(o*2,l,mid,q,v);
else update(o*2+1,mid+1,r,q,v);
pushup(o);
}
int querysum(int o,int l,int r,int ql,int qr){
int mid=(l+r)/2,ans=0;
if (ql<=l&&r<=qr)return sumv[o];
if (ql<=mid)ans+=querysum(o*2,l,mid,ql,qr);
if (qr>mid)ans+=querysum(o*2+1,mid+1,r,ql,qr);
pushup(o);
return ans;
}
int querymax(int o,int l,int r,int ql,int qr){
int mid=(l+r)/2,ans=-inf;
if (ql<=l&&r<=qr)return maxv[o];
if (ql<=mid)ans=max(ans,querymax(o*2,l,mid,ql,qr));
if (qr>mid)ans=max(ans,querymax(o*2+1,mid+1,r,ql,qr));
pushup(o);
return ans;
}
int qsum(int u,int v){
int ans=0;
while (top[u]!=top[v]){
if (d[top[u]]<d[top[v]])swap(u,v);
ans+=querysum(1,1,n,tpos[top[u]],tpos[u]);
u=fa[top[u]];
}
if (d[u]<d[v])swap(u,v);
ans+=querysum(1,1,n,tpos[v],tpos[u]);
return ans;
}
int qmax(int u,int v){
int ans=-inf;
while (top[u]!=top[v]){
if (d[top[u]]<d[top[v]])swap(u,v);
ans=max(ans,querymax(1,1,n,tpos[top[u]],tpos[u]));
u=fa[top[u]];
}
if (d[u]<d[v])swap(u,v);
ans=max(ans,querymax(1,1,n,tpos[v],tpos[u]));
return ans;
}
int main(){
memset(head,0,sizeof(head));
memset(a,0,sizeof(a));
scanf("%d",&n);
for (int i=1;i<n;i++){
int u,v;
scanf("%d%d",&u,&v);
addedge(u,v);
}
for (int i=1;i<=n;i++)scanf("%d",&a[i]);
d[1]=1;fa[1]=1;dfs1(1,-1);dfs2(1,1);build(1,1,n);
scanf("%d",&q);
while (q--){
int x,y;
char s[10];
scanf("%s%d%d",s,&x,&y);
if (s[1]=='H')update(1,1,n,tpos[x],y);
if (s[1]=='M')printf("%d\n",qmax(x,y));
if (s[1]=='S')printf("%d\n",qsum(x,y));
}
return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const int MAXN = 250000+100;
struct Seg_Tree{
int sm[MAXN<<1];
inline int lowbit(int _x){
return _x&(-_x);
}
void build (int l,int r){
for (int i=l;i<=r;i++){
add(i,1);
}
}
void add(int x,int val){
while (x<=MAXN){
sm[x]+=val;
x+=lowbit(x);
}
}
int sum(int x){
int res =0;
while (x){
res+=sm[x];
x-=lowbit(x);
}
return res;
}
int query_sum(int l,int r){
return sum(r)-sum(l-1);
}
}tree;
int first[MAXN*2];
int nxt[MAXN*2];
int des[MAXN*2];
int tpos[MAXN];
int deep[MAXN];
int top[MAXN];
int fa[MAXN];
int wson[MAXN];
int size[MAXN];
int n,q,tot=0,cnt=0;
char s[10];
inline void add(int _u,int _v){
des[++tot] = _v;
nxt[tot] = first[_u];
first[_u] = tot;
}
void input(){
scanf("%d",&n);
for (int i=1;i<n;i++){
int u,v;
scanf("%d%d",&u,&v);
add(u,v);
add(v,u);
}
}
void dfs(int node,int father){
deep[node] = deep[father]+1;
fa[node] = father;
size[node] =1;
for (int t = first[node];t;t = nxt[t]){
int v = des[t];
if (v==father){
continue;
}
dfs(v,node);
if (size[v]>size[wson[node]]){
wson[node] = v;
}
size[node]+=size[v];
}
}
void dfs2(int node,int father,int chain){
top[node] = chain;
tpos[node] = ++cnt;
if (wson[node]){
dfs2(wson[node],node,chain);
}
for (int t = first[node];t;t = nxt[t]){
int v = des[t];
if (v==father||v ==wson[node]){
continue;
}
dfs2(v,node,v);
}
}
void init(){
dfs(1,0);
dfs2(1,0,1);
tree.build(2,n);
}
int get_sum(int u,int v){
int res =0;
while (top[u]!=top[v]){
if (deep[top[u]]<deep[top[v]]){
swap(u,v);
}
res+= tree.query_sum(tpos[top[u]],tpos[u]);
u = fa[top[u]];
}
if (deep[u]<deep[v]){
swap(u,v);
}
res += tree.query_sum(tpos[v],tpos[u]);
return res;
}
void modify(int u,int v){
if (fa[u]!=v){
swap(u,v);
}
tree.add(tpos[u],-1);
}
void solve(){
scanf("%d",&q);
q+=n-1;
while (q--){
scanf("%s",s);
if (s[0]=='W'){
int x;
scanf("%d",&x);
printf("%d\n",get_sum(1,x));
}else{
int x,y;
scanf("%d%d",&x,&y);
modify(x,y);
}
}
}
int main(){
input();
init();
solve();
return 0;
}