【树链剖分模板】bzoj1036 树的统计

#include<cstdio>
#include<algorithm>
using namespace std;
const int N=30000+5;
 
int n,v[N];
 
int num,last[N],nxt[2*N],ver[2*N];
inline void add(int x,int y)
 {nxt[++num]=last[x]; last[x]=num; ver[num]=y;
 }
 
int siz[N],son[N],fa[N],deep[N];
void build(int x)
 {siz[x]=1; son[x]=0;
  
  for(int i=last[x];i;i=nxt[i])
   {int y=ver[i];
    
    if(y!=fa[x])
     {fa[y]=x;  deep[y]=deep[x]+1;
      build(y);
       
      if(siz[y]>siz[son[x]]) son[x]=y;
      siz[x]+=siz[y];
     }
   }
 }
 
int id,a[N],top[N],ord[N];
void dfs(int x)
 {a[++id]=v[x];  ord[x]=id;
   
  if(x==son[fa[x]]) top[x]=top[fa[x]];
  else              top[x]=x;
   
  if(son[x]) dfs(son[x]);
  for(int i=last[x];i;i=nxt[i])
   if(ver[i]!=fa[x] && ver[i]!=son[x])
     dfs(ver[i]);
 }
  
struct point{int l,r,sum,maxx;}t[4*N];   
 
void build(int i,int p,int q)
 {t[i].l=p; t[i].r=q;
  if(p==q)  {t[i].maxx=t[i].sum=a[p]; return;}
   
  int mid=p+q>>1;
  build(2*i,p,mid);
  build(2*i+1,mid+1,q);
   
  t[i].sum=t[2*i].sum+t[2*i+1].sum;
  t[i].maxx=max(t[2*i].maxx,t[2*i+1].maxx);     
 }
 
void change(int i,int p,int x) 
 {if(t[i].l==t[i].r && t[i].l==p) {t[i].maxx=t[i].sum=x; return;}
   
  int mid=t[i].l+t[i].r>>1;
  if(p<=mid) change(2*i,p,x);
  else       change(2*i+1,p,x);
   
  t[i].sum=t[2*i].sum+t[2*i+1].sum;
  t[i].maxx=max(t[2*i].maxx,t[2*i+1].maxx);     
 }
  
point ask(int i,int p,int q)
 {if(p<=t[i].l && t[i].r<=q) return t[i];
   
  int mid=t[i].l+t[i].r>>1;
  if(q<=mid)     return ask(2*i,p,q);
  else if(p>mid) return ask(2*i+1,p,q);
  else         {point re,r1=ask(2*i,p,q),r2=ask(2*i+1,p,q);
   
                re.sum=r1.sum+r2.sum; re.maxx=max(r1.maxx,r2.maxx);
                return re;
               }   
 } 
  
inline point query(int x,int y)
 {point re; re.sum=0; re.maxx=-30005;
  
  while(top[x]!=top[y])
   {if(deep[top[x]]<deep[top[y]]) swap(x,y);
    
    point k=ask(1,ord[top[x]],ord[x]);
    re.sum+=k.sum; re.maxx=max(re.maxx,k.maxx);
     
    x=fa[top[x]];
   }
  if(deep[x]<deep[y]) swap(x,y);
   
  point k=ask(1,ord[y],ord[x]);
  re.sum+=k.sum; re.maxx=max(re.maxx,k.maxx);
   
  return re;
 } 
int main()
 { 
 scanf("%d",&n);  int x,y,m; char op[15];
  
 for(int i=1;i<n;i++) 
  {scanf("%d%d",&x,&y);
   add(x,y); add(y,x);
  }
   
 for(int i=1;i<=n;i++) scanf("%d",&v[i]);
  
 deep[1]=1; build(1);    dfs(1);
 build(1,1,id);
  
 scanf("%d",&m); 
  
 while(m--)
  {scanf("%s%d%d",op,&x,&y);
    
   if(op[1]=='H')    change(1,ord[x],y);       
   else if(op[1]=='M') {point ans=query(x,y);
                        printf("%d\n",ans.maxx);}
   else if(op[1]=='S') {point ans=query(x,y);
                        printf("%d\n",ans.sum);}
  }
return 0;
 }