LightOJ 1348（Aladdin and the Return Journey ）

题目链接：传送门

题目大意：一棵无根树，每个点上有权值，两种操作，0 x y询问x~y路径上权值和 1 x y将

　　　　　节点 x 权值变为y。对于询问操作输出答案。

题目思路：树链剖分

 #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,k,v,head[N],a[N],hcnt,L,R;
 struct Edge{int to,nxt;}node[N<<];
 int son[N],siz[N],id[N],tid;
 int fa[N],top[N],dep[N],posi[N];
 LL seg[N<<];
 void init(){
     mst(head,-);mst(id,);mst(siz,);
     mst(son,);hcnt=tid=;
 }
 void dfs1(int u,int f,int deep){
     fa[u]=f,dep[u]=deep,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);
     }
 }
 void build(int rt,int l,int r){
     if(l==r){seg[rt]=a[posi[l]];return;}
     int mid=l+r>>;
     build(lson);build(rson);
     seg[rt]=seg[rt<<]+seg[rt<<|];
 }
 void update(int rt,int l,int r){
     if(l==r){seg[rt]=v;return;}
     int mid=l+r>>;
     if(L<=mid)update(lson);
     else update(rson);
     seg[rt]=seg[rt<<]+seg[rt<<|];
 }
 LL query(int rt,int l,int r){
     if(L<=l&&r<=R)return seg[rt];
     int mid=l+r>>;LL temp=;
     if(L<=mid)temp+=query(lson);
     if(R>mid) temp+=query(rson);
     return temp;
 }
 void lca(int x,int y){
     LL 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[y],R=id[x];
     res+=query(,,n);
     printf("%lld\n",res);
 }
 int main(){
     int i,j,group,x,y,Case=;
     group=read();
     while(group--){
         init();
         n=read();
         for(i=;i<=n;++i)a[i]=read();
         for(i=;i<n;++i){
             x=read(),y=read();
             ++x;++y;
             node[hcnt].to=y,node[hcnt].nxt=head[x],head[x]=hcnt++;
             node[hcnt].to=x,node[hcnt].nxt=head[y],head[y]=hcnt++;
         }
         dfs1(,,);dfs2(,);build(,,n);
         m=read();
         printf("Case %d:\n",++Case);
         while(m--){
             x=read();
             if(!x){
                 x=read(),y=read();
                 ++x;++y;
                 lca(x,y);
             }
             else{
                 x=read(),y=read();
                 ++x;
                 L=id[x],v=y;
                 update(,,n);
             }
         }
     }
     return ;
 }