BZOJ 1036: [ZJOI2008]树的统计Count

#include<cstdio>
#include<cstring>
#include<iostream>
#define lc k<<1
#define rc k<<1|1
#define IN inline
#define R register
using namespace std;
const int N=3e5+10;
IN int read(){
    R int x=0;R bool f=1;
    R char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=0;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=(x<<3)+(x<<1)+ch-‘0‘;ch=getchar();}
    return f?x:-x;
}
struct node{
    int u,v,next;
}e[N<<1];
int n,m,T,tot,num,head[N],v[N],fa[N],top[N],pos[N],dep[N],siz[N],son[N];
int mx[N<<2],sum[N<<2];
void add(int x,int y){
    e[++tot].u=x;
    e[tot].v=y;
    e[tot].next=head[x];
    head[x]=tot;
}
void dfs(int u,int f,int de){
    fa[u]=f;dep[u]=de;siz[u]=1;
    for(int i=head[u],v;i;i=e[i].next){
        v=e[i].v;
        if(v!=f){
            dfs(v,u,de+1);
            siz[u]+=siz[v];
            if(!son[u]||siz[son[u]]<siz[v]){
                son[u]=v;
            }
        }
    }
}
void getpos(int u,int tp){
    top[u]=tp;
    pos[u]=++num;
    if(!son[u]) return ;
    getpos(son[u],tp);
    for(int i=head[u],v;i;i=e[i].next){
        v=e[i].v;
        if(v!=son[u]&&v!=fa[u]){
            getpos(v,v);
        }
    }
}
void change(int k,int l,int r,int pos,int val){
    if(l==r){
        mx[k]=sum[k]=val;
        return;
    }
    int mid=l+r>>1;
    if(pos<=mid) change(lc,l,mid,pos,val);
    else change(rc,mid+1,r,pos,val);
    mx[k]=max(mx[lc],mx[rc]);
    sum[k]=sum[lc]+sum[rc];
}
int qmax(int k,int l,int r,int x,int y){
    if(l==x&&y==r) return mx[k];
    int mid=l+r>>1;
    if(y<=mid) return qmax(lc,l,mid,x,y);
    else if(x>mid) return qmax(rc,mid+1,r,x,y);
    else return max(qmax(lc,l,mid,x,mid),qmax(rc,mid+1,r,mid+1,y));
}
int findmax(int u,int v){
    int tp1=top[u],tp2=top[v],ans=-0x3f3f3f3f;
    while(tp1!=tp2){
        if(dep[tp1]<dep[tp2]){
            swap(tp1,tp2);
            swap(u,v);
        }
        ans=max(ans,qmax(1,1,n,pos[tp1],pos[u]));
        u=fa[tp1];tp1=top[u];
    }
    if(dep[u]>dep[v]) swap(u,v);
    ans=max(ans,qmax(1,1,n,pos[u],pos[v]));
    return ans;
}
int qsum(int k,int l,int r,int x,int y){
    if(l==x&&y==r) return sum[k];
    int mid=l+r>>1;
    if(y<=mid) return qsum(lc,l,mid,x,y);
    else if(x>mid) return qsum(rc,mid+1,r,x,y);
    else return qsum(lc,l,mid,x,mid)+qsum(rc,mid+1,r,mid+1,y);
}
int findsum(int u,int v){
    int tp1=top[u],tp2=top[v],ans=0;
    while(tp1!=tp2){
        if(dep[tp1]<dep[tp2]){
            swap(tp1,tp2);
            swap(u,v);
        }
        ans+=qsum(1,1,n,pos[tp1],pos[u]);
        u=fa[tp1];tp1=top[u];
    }
    if(dep[u]>dep[v]) swap(u,v);
    ans+=qsum(1,1,n,pos[u],pos[v]);
    return ans;
}
int main(){
    n=read();
    for(int i=1,x,y,z;i<n;i++){
        x=read();y=read();
        add(x,y);add(y,x);
    }
    for(int i=1;i<=n;i++) v[i]=read();
    dfs(1,0,1);
    getpos(1,1);
    for(int i=1;i<=n;i++) change(1,1,n,pos[i],v[i]); 
    char ch[20];
    m=read();
    for(int x,y;m--;){
        scanf("%s",ch);x=read();y=read();
        if(ch[0]==‘C‘){
            change(1,1,num,pos[x],v[x]=y);
        }
        else{
            if(ch[1]==‘M‘) printf("%d\n",findmax(x,y));
            else printf("%d\n",findsum(x,y));
        }
    }
    return 0;
}