HYSBZ1036 树链剖分

#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 = 50010;
struct node
{
int to;
int v;
int next;
}edge[MAXN*3];
int pre[MAXN],ind,top[MAXN],fa[MAXN],son[MAXN],w[MAXN],deq[MAXN],siz[MAXN],fn;
int tree1[MAXN<<2],tree2[MAXN<<2];
int n,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] = 0;
fa[rt] = pa;
siz[rt] = 1;
for(int i=pre[rt]; i!=-1; i=edge[i].next){
int t = edge[i].to;
if(t != fa[rt]){
dfs1(t,rt,d+1);
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] != 0)
dfs2(son[rt],tp);
for(int i=pre[rt]; i!=-1; i=edge[i].next){
int t = edge[i].to;
if(son[rt] != t && t != fa[rt]){
dfs2(t,t);
}
}
}
void pushup1(int rt)
{
tree1[rt] = max(tree1[rt<<1],tree1[rt<<1|1]);
}
void pushup2(int rt)
{
tree2[rt] = tree2[rt<<1] + tree2[rt<<1|1];
}
void Insert(int p,int v,int l,int r,int rt)
{
if(l == r){
tree1[rt] = tree2[rt] = v;
return ;
}
int m = (l+r)/2;
if(m >= p){
Insert(p,v,lson);
}
else {
Insert(p,v,rson);
}
pushup1(rt);
pushup2(rt);
}
void updata(int p,int v,int l,int r,int rt)
{
if(l == r){
tree1[rt] = v;
tree2[rt] = v;
return ;
}
int m = (l+r)/2;
if(m >= p){
updata(p,v,lson);
}
else {
updata(p,v,rson);
}
pushup1(rt);
pushup2(rt);
}
int query1(int L,int R,int l,int r,int rt)
{
if(L<=l && r<=R){
return tree1[rt];
}
int m = (l+r)/2;
int ans = -INF;
if(m >= L){
ans = max(ans,query1(L,R,lson));
}
if(m < R){
ans = max(ans,query1(L,R,rson));
}
return ans;
}
int query2(int L,int R,int l,int r,int rt)
{
if(L<=l && r<=R){
return tree2[rt];
}
int m = (l+r)/2;
int ans = 0;
if(m >= L){
ans += query2(L,R,lson);
}
if(m < R){
ans += query2(L,R,rson);
}
return ans;
}
int Getmax(int x,int y)
{
int ans = -INF;
while(top[x] != top[y])
{
if(deq[top[x]] < deq[top[y]]){
swap(x,y);
}
ans = max(ans,query1(w[top[x]],w[x],1,fn,1));
x = fa[top[x]];
}
if(deq[x] < deq[y]){
swap(x,y);
}
ans = max(ans,query1(w[y],w[x],1,fn,1));
return ans;
}
int Getsum(int x,int y)
{
int ans = 0;
while(top[x] != top[y])
{
if(deq[top[x]] < deq[top[y]]){
swap(x,y);
}
ans += query2(w[top[x]],w[x],1,fn,1);
x = fa[top[x]];
}
if(deq[x] < deq[y]){
swap(x,y);
}
ans += query2(w[y],w[x],1,fn,1);
return ans;
}
int main()
{
int i;
while(~scanf("%d",&n))
{
ind = 1;
memset(pre,-1,sizeof(pre));
memset(tree1,0,sizeof(tree1));
memset(tree2,0,sizeof(tree2));
for(i=1; i<n; i++){
int x,y;
scanf("%d%d",&x,&y);
add(x,y);
add(y,x);
}
for(i=1; i<=n; i++){
scanf("%d",&val[i]);
}
dfs1(1,1,1);

fn = 0;
dfs2(1,1);

for(i=1; i<=n; i++){
Insert(w[i],val[i],1,fn,1);
}
int q;
char s[10];
scanf("%d",&q);
while(q--)
{
scanf("%s",s);
int x,y;
scanf("%d%d",&x,&y);
if(s[0] == 'C'){
updata(w[x],y,1,fn,1);
}
else if(s[1] == 'S'){
printf("%d\n",Getsum(x,y));
}
else {
printf("%d\n",Getmax(x,y));
}
}
}
}