bzoj3931 zjoi2008 树的统计 count

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<vector>

using namespace std;

const int Maxn=30010,Maxm=30010,INF=~0u>>1;

int n;

struct Data{
    int sum,max;
    Data (int sum=0,int max=-INF):sum(sum),max(max){}
    Data operator + (const Data& rhs)const{
        return Data(sum+rhs.sum,std::max(max,rhs.max));
    }
};

struct SegmentTree{
    Data da[Maxn*4];
    int lft,rgt,w;
    void pp(int l,int r=0){ 
        lft=l;rgt=r;
    }
    void change(int s,int l,int r){
        if(l==r && l==lft){
            da[s]=Data(w,w);
            return;     
        }
        int mid=(l+r)>>1;
        if(lft<=mid) change(s<<1,l,mid);
        else change(s<<1|1,mid+1,r);
        da[s]=da[s<<1]+da[s<<1|1];
    }
    Data query(int s,int l,int r){
        if(lft<=l && r<=rgt) return da[s];
        int mid=(l+r)>>1;
        if(rgt<=mid) return query(s<<1,l,mid);
        if(mid<lft) return query(s<<1|1,mid+1,r);
        return query(s<<1,l,mid) + query(s<<1|1,mid+1,r);
    }
}seg;

int en[Maxm*2],next[Maxm*2],fir[Maxn],tot;

void Add(int from,int to){
    en[++tot] = to;
    next[tot] = fir[from];
    fir[from] = tot;
}

int sz[Maxn],fa[Maxn],son[Maxn],dep[Maxn];

void dfs(int u){
    sz[u]=1;
    son[u]=0;
    for(int k=fir[u];k;k=next[k]){
        int v=en[k];
        if(v == fa[u]) continue;
        fa[v] = u;
        dep[v]=dep[u]+1;
        dfs(v);
        sz[u]+=sz[v];
        if(sz[v]>sz[son[u]]) son[u] = v;
    }
}

int pos[Maxn],top[Maxn],tm;

void build(int u,int pre){
    top[u]=pre;
    pos[u]=++tm;
    if(son[u]) build(son[u],pre);
    for(int k=fir[u];k;k=next[k]){
        int v=en[k];
        if(v==fa[u] || v==son[u]) continue;
        build(v,v);
    }
}

Data query(int a,int b){
    int ta=top[a],tb=top[b];
    Data ret;
    for(;ta!=tb;a=fa[ta],ta=top[a]){
        if(dep[ta]<dep[tb]) swap(a,b), swap(ta,tb);
        seg.pp(pos[ta],pos[a]);
        ret=ret+seg.query(1,1,n);
    }
    if(dep[a]>dep[b]) swap(a,b);
    seg.pp(pos[a],pos[b]);
    return ret+seg.query(1,1,n);
}
    
int main(){
#ifdef DEBUG
    freopen("in.txt","r",stdin);
    freopen("my.out","w",stdout);
#endif
    
    scanf("%d",&n);
    for(int i=1;i<n;i++){
        int u,v;
        scanf("%d%d",&u,&v);
        Add(u,v);
        Add(v,u);
    }
    
    dfs(1);
    build(1,1);
    
    for(int i=1;i<=n;i++){
        seg.pp(pos[i]);
        scanf("%d",&seg.w);
        seg.change(1,1,n);
    }
    
    int m;
    scanf("%d",&m);
    char cmd[10];
    int a,b;
    
    for(;m--;){
        scanf("%s%d%d",cmd,&a,&b);
        if(cmd[0]==‘C‘) seg.lft=pos[a],seg.w=b,seg.change(1,1,n);
        else if(cmd[1]==‘S‘) printf("%d\n",query(a,b).sum);
        else printf("%d\n",query(a,b).max);
    }
    
    return 0;
}