题意：区间+，子树求和
解法：树剖维护一颗线段树，子树求和用DFS序即可。
///BZOJ 2836
#include <bits/stdc++.h>
using namespace std;
const int maxn = 200010;
int n, m, edgecnt, tim, siz[maxn], top[maxn], son[maxn], dep[maxn], tid[maxn], fa[maxn], head[maxn], L[maxn], R[maxn];
typedef long long LL;
struct edge{
int v, next;
}E[maxn*2];
struct seg{
int l,r;
LL sum, lazy;
}tree[maxn*4];
void init(){
memset(head, -1, sizeof(head));
memset(son, -1, sizeof(son));
edgecnt=tim=0;
}
void addedge(int u, int v){
E[edgecnt].v=v,E[edgecnt].next=head[u],head[u]=edgecnt++;
}
void dfs1(int u, int father, int d){
dep[u]=d;
fa[u]=father;
siz[u]=1;
for(int i=head[u];~i;i=E[i].next){
int v=E[i].v;
if(v==father) continue;
dfs1(v,u,d+1);
siz[u]+=siz[v];
if(son[u]==-1||siz[v]>siz[son[u]]) son[u]=v;
}
}
void dfs2(int u, int tp){
top[u]=tp;
L[u]=tid[u]=++tim;
R[u]=tim;
if(son[u]==-1) return;
dfs2(son[u],tp);
for(int i=head[u];~i;i=E[i].next){
int v=E[i].v;
if(v!=son[u]&&v!=fa[u]) dfs2(v,v);
}
R[u]=tim;
}
void pushup(int rt){
tree[rt].sum=tree[rt*2].sum+tree[rt*2+1].sum;
}
void pushdown(int rt){
if(tree[rt].lazy){
int mid=(tree[rt].l+tree[rt].r)/2;
tree[rt*2].sum+=tree[rt].lazy*(LL)(mid-tree[rt].l+1);
tree[rt*2].lazy+=tree[rt].lazy;
tree[rt*2+1].sum+=tree[rt].lazy*(LL)(tree[rt].r-mid);
tree[rt*2+1].lazy+=tree[rt].lazy;
tree[rt].lazy=0;
}
}
void build(int l, int r, int rt){
tree[rt].l=l,tree[rt].r=r,tree[rt].sum=tree[rt].lazy=0;
if(l==r) return;
int mid=(l+r)/2;
build(l,mid,rt*2);
build(mid+1,r,rt*2+1);
pushup(rt);
}
void update(int L, int R, LL v, int rt){
if(L<=tree[rt].l&&tree[rt].r<=R){
tree[rt].lazy+=v;
tree[rt].sum+=v*(LL)(tree[rt].r-tree[rt].l+1);
return;
}
pushdown(rt);
int mid=(tree[rt].l+tree[rt].r)/2;
if(L<=mid) update(L,R,v,rt*2);
if(mid<R) update(L,R,v,rt*2+1);
pushup(rt);
}
LL query(int L, int R, int rt){
if(L<=tree[rt].l&&tree[rt].r<=R){
return tree[rt].sum;
}
pushdown(rt);
int mid=(tree[rt].l+tree[rt].r)/2;
LL ans = 0;
if(L<=mid) ans+=query(L,R,rt*2);
if(mid<R) ans+=query(L,R,rt*2+1);
return ans;
}
void change(int u, int v, LL c){
int f1=top[u],f2=top[v];
while(f1!=f2){
if(dep[f1]<dep[f2]) swap(f1,f2),swap(u,v);
update(tid[f1],tid[u],c,1);
u=fa[f1];
f1=top[u];
}
if(dep[u]>dep[v]) swap(u,v);
update(tid[u],tid[v],c,1);
}
int main()
{
scanf("%d", &n);
init();
for(int i=1; i<n; i++){
int u,v;
scanf("%d%d", &u,&v);
u++;v++;
addedge(u,v);
addedge(v,u);
}
dfs1(1,1,1);
dfs2(1,1);
build(1,n,1);
scanf("%d", &m);
while(m--){
char op[10];
scanf("%s", op);
int x, y;
LL c;
if(op[0]=='A'){
scanf("%d%d%lld", &x,&y,&c);
x++;
y++;
change(x,y,c);
}
else{
scanf("%d", &x);
++x;
printf("%lld\n", query(L[x],R[x],1));
}
}
return 0;
}
/*
5
0 1
1 2
1 3
0 4
*/
