HYSBZ 1036（树的统计Count）

题目链接：传送门

题目大意：中文题，略

题目思路：树链剖分裸题。

闲谈：树链越练越熟练了

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cmath>
 #include <algorithm>
 #include <cstring>
 #include <stack>
 #include <cctype>
 #include <queue>
 #include <string>
 #include <vector>
 #include <set>
 #include <map>
 #include <climits>
 #define lson rt<<1,l,mid
 #define rson rt<<1|1,mid+1,r
 #define fi first
 #define se second
 #define ping(x,y) ((x-y)*(x-y))
 #define mst(x,y) memset(x,y,sizeof(x))
 #define mcp(x,y) memcpy(x,y,sizeof(y))
 using namespace std;
 #define gamma 0.5772156649015328606065120
 #define MOD 1000000007
 #define inf 0x3f3f3f3f
 #define N 30005
 #define maxn 30010
 typedef pair<int,int> PII;
 typedef long long LL;
 LL read(){
     LL x=,f=;char ch=getchar();
     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}
     while(ch>=''&&ch<=''){x=(x<<)+(x<<)+ch-'';ch=getchar();}
     return x*f;
 }

 int n,m,flag,L,R;
 int son[N],siz[N],top[N],id[N],tid,a[N];
 int dep[N],posi[N],fa[N],head[N],hcnt;
 struct Node{int to,nxt,v;}node[maxn<<];
 struct Seg{int sum,v;}seg[N<<];
 inline void init(){
     mst(head,-);tid=hcnt=;mst(siz,);mst(son,);mst(id,);
 }
 void dfs1(int u,int f,int deep){
     dep[u]=deep,fa[u]=f,siz[u]++;
     for(int i=head[u];~i;i=node[i].nxt){
         int e=node[i].to;
         if(e==f)continue;
         dfs1(e,u,deep+);
         siz[u]+=siz[e];
         if(!son[u]||siz[son[u]]<siz[e])
             son[u]=e;
     }
 }
 void dfs2(int u,int tp){
     top[u]=tp,id[u]=++tid,posi[tid]=u;
     if(!son[u])return;dfs2(son[u],tp);
     for(int i=head[u];~i;i=node[i].nxt){
         int e=node[i].to;
         if(!id[e])dfs2(e,e);
     }
 }
 inline void pushup(int rt){
     seg[rt].sum=seg[rt<<].sum+seg[rt<<|].sum;
     seg[rt].v=max(seg[rt<<].v,seg[rt<<|].v);
 }
 void build(int rt,int l,int r){
     if(l==r){seg[rt].v=seg[rt].sum=a[posi[l]];return;}
     int mid=l+r>>;
     build(lson);build(rson);
     pushup(rt);
 }
 void update(int rt,int l,int r,int v){
     if(l==r){seg[rt].v=seg[rt].sum=v;return;}
     int mid=l+r>>;
     if(L<=mid)update(lson,v);
     else update(rson,v);
     pushup(rt);
 }
 int query(int rt,int l,int r){
     if(L<=l&&r<=R){if(flag==)return seg[rt].v;return seg[rt].sum;}
     int mid=l+r>>;
     int temp;
     if(flag){
         temp=;
         if(L<=mid)temp+=query(lson);
         if(R>mid) temp+=query(rson);
     }
     else{
         temp=-inf;
         if(L<=mid)temp=max(temp,query(lson));
         if(R>mid) temp=max(temp,query(rson));
     }
     return temp;
 }
 void lca(int x,int y,int fl){
     flag=fl;
     if(fl){
         int res=;
         while(top[x]!=top[y]){
             if(dep[top[x]]<dep[top[y]])swap(x,y);
             L=id[top[x]],R=id[x];
             res+=query(,,n);
             x=fa[top[x]];
         }
         if(dep[x]>dep[y])swap(x,y);
         L=id[x],R=id[y];
         res+=query(,,n);
         printf("%d\n",res);
     }
     else{
         int res=-inf;
         while(top[x]!=top[y]){
             if(dep[top[x]]<dep[top[y]])swap(x,y);
             L=id[top[x]],R=id[x];
             res=max(res,query(,,n));
             x=fa[top[x]];
         }
         if(dep[x]>dep[y])swap(x,y);
         L=id[x],R=id[y];
         res=max(res,query(,,n));
         printf("%d\n",res);
     }
 }
 int main(){
     int i,j,group,x,y,v;
     while(scanf("%d",&n)!=EOF){
         init();
         for(i=;i<n;++i){
             x=read(),y=read();
             node[hcnt].to=y,node[hcnt].nxt=head[x],head[x]=hcnt++;
             node[hcnt].to=x,node[hcnt].nxt=head[y],head[y]=hcnt++;
         }
         for(i=;i<=n;++i)a[i]=read();
         dfs1(,,);dfs2(,);build(,,n);
         m=read();
         char str[];
         while(m--){
             scanf("%s",str);x=read(),y=read();
             if(strcmp(str,"QMAX")==) lca(x,y,);
             else if(strcmp(str,"QSUM")==) lca(x,y,);
             else L=id[x],update(,,n,y);
         }
     }
     return ;
 }