给你n个点，m条边，p次操作。n个点相连后是一棵树。每次操作可以是x 到 y 增加 z，或者减z，或者问当前点的值是多少。
可以将树分成链，每个点在线段树上都有自己的点，然后线段树成段更新一下。
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<queue>
#include<stack>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define INF 99999999
#define ll __int64
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
using namespace std;
const int MAXN = ;
struct node
{
int to;
int v;
int next;
}edge[MAXN*];
int pre[MAXN],ind,top[MAXN],fa[MAXN],son[MAXN],w[MAXN],deq[MAXN],siz[MAXN],fn;
int tree[MAXN<<],mark[MAXN<<];
int n,m,val[MAXN];
void add(int x,int y)
{
edge[ind].to = y;
edge[ind].next = pre[x];
pre[x] = ind++;
}
void dfs1(int rt,int pa,int d)
{
deq[rt] = d;
son[rt] = ;
fa[rt] = pa;
siz[rt] = ;
int i;
for(i=pre[rt]; i!=-; i=edge[i].next){
int t = edge[i].to;
if(t != fa[rt]){
dfs1(t,rt,d+);
siz[rt] += siz[t];
if(siz[son[rt]] < siz[t]){
son[rt] = t;
}
}
}
}
void dfs2(int rt,int tp)
{
w[rt] = ++fn;
top[rt] = tp;
if(son[rt] != )
dfs2(son[rt], tp);
for(int i=pre[rt]; i!=-; i=edge[i].next){
int t = edge[i].to;
if(t != son[rt] && t != fa[rt]){
dfs2(t,t);
}
}
}
void build(int l,int r,int rt)
{
tree[rt] = ;
mark[rt] = ;
if(l == r)
return ;
int m = (l+r)/;
build(lson);
build(rson);
}
void pushdown(int rt)
{
if(mark[rt] != ){
mark[rt<<|] += mark[rt];
mark[rt<<] += mark[rt];
tree[rt<<|] += mark[rt];
tree[rt<<] += mark[rt];
mark[rt] = ;
}
}
void Insert(int p,int v,int l,int r,int rt)
{
if(l == r){
tree[rt] = v;
return ;
}
int m = (l+r)/;
if(m >= p){
Insert(p,v,lson);
}
else Insert(p,v,rson);
}
void updata(int L,int R,int v,int l,int r,int rt)
{
if(L<=l && r<=R){
mark[rt] += v;
tree[rt] += v;
return ;
}
pushdown(rt); int m = (l+r)/;
if(m >= L){
updata(L,R,v,lson);
}
if(m < R){
updata(L,R,v,rson);
}
}
int query(int p,int l,int r,int rt)
{
if(l == r){
return tree[rt];
}
pushdown(rt);
int m = (l+r)/;
if(m >= p){
return query(p,lson);
}
else {
return query(p,rson);
}
}
void updata_all(int x,int y,int z)
{
while(top[x] != top[y])
{
if(deq[top[x]] < deq[top[y]]){
swap(x,y);
}
updata(w[top[x]],w[x],z,,fn,); x = fa[top[x]];
}
if(deq[x] < deq[y]){
swap(x,y);
}
updata(w[y],w[x],z,,fn,);
}
int main()
{
int i,j,p;
while(~scanf("%d%d%d",&n,&m,&p))
{
for(i=; i<=n; i++){
scanf("%d",&val[i]);
}
ind = ;
memset(pre,-,sizeof(pre));
for(i=; i<=m; i++){
int x,y;
scanf("%d%d",&x,&y);
add(x,y);
add(y,x);
}
dfs1(,,);
fn = ;
dfs2(,); build(,n,);
for(i=; i<=n; i++){
Insert(w[i],val[i],,fn,);
}
char s[];
while(p--)
{
scanf("%s",s);
if(s[] == 'I'){
int x,y,z;
scanf("%d%d%d",&x,&y,&z);
updata_all(x,y,z);
}
else if(s[] == 'D'){
int x,y,z;
scanf("%d%d%d",&x,&y,&z);
updata_all(x,y,-z);
}
else {
int x;
scanf("%d",&x);
printf("%d\n",query(w[x],,fn,));
}
}
}
}