suoi22 WRX知识树(dfs序)

把一条路径拆成到根的四个链（两端点、lca和fa[lca]），然后给dfs序中链的端点做单点修改、区间查询它的子树和再加上它原来的权值就可以了

 #include<bits/stdc++.h>
 #define pa pair<int,int>
 #define lowb(x) ((x)&(-(x)))
 #define REP(i,n0,n) for(i=n0;i<=n;i++)
 #define PER(i,n0,n) for(i=n;i>=n0;i--)
 #define MAX(a,b) ((a>b)?a:b)
 #define MIN(a,b) ((a<b)?a:b)
 #define CLR(a,x) memset(a,x,sizeof(a))
 #define rei register int
 using namespace std;
 typedef long long ll;
 const int maxn=1e6+;

 inline ll rd(){
     ll x=;char c=getchar();int neg=;
     while(c<''||c>''){if(c=='-') neg=-;c=getchar();}
     while(c>=''&&c<='') x=x*+c-'',c=getchar();
     return x*neg;
 }

 int N,M;
 int eg[maxn*][],egh[maxn],ect;
 int v[maxn],fa[maxn],bfa[maxn];
 int lq[maxn*][],lqh[maxn],lca[maxn][];
 int dfn[maxn][],tot;
 int stk[maxn][],sh;
 ll tr[maxn];
 int que[maxn];
 bool vis[maxn];

 inline void adeg(int a,int b){
     eg[++ect][]=b;eg[ect][]=egh[a];egh[a]=ect;
 }

 int getf(int x){return x==bfa[x]?x:bfa[x]=getf(bfa[x]);}

 inline void add(int x,ll y){
     for(;x>&&x<=N;x+=lowb(x)) tr[x]+=y;
 }
 inline ll query(int x){
     ll re=;for(;x>;x-=lowb(x)) re+=tr[x];return re;
 }

 void dfs(){
     stk[sh=][]=;stk[][]=egh[];
     dfn[][]=tot=;
     while(sh){
         int x=stk[sh][],i=stk[sh][],b=eg[i][];
         vis[x]=;
         if(!i){
             for(int j=lqh[x];j;j=lq[j][]){
                 int c=lq[j][];
                 if(vis[c]) lca[j>>][]=getf(c);
             }
             bfa[getf(x)]=fa[x];
             dfn[x][]=tot;
             sh--;continue;
         }
         stk[sh][]=eg[i][];
         if(!vis[b]){
             fa[b]=x;stk[++sh][]=b,stk[sh][]=egh[b];
             dfn[b][]=++tot;
         }

     }
 }

 int main(){
     //freopen(".in","r",stdin);
     rei i;
     N=rd(),M=rd();
     for(i=;i<=N;i++) v[i]=rd();
     for(i=;i<N;i++){
         int a=rd(),b=rd();
         adeg(a,b);adeg(b,a);
     }for(i=;i<=N;i++) bfa[i]=i;
     for(i=;i<=M;i++){
         int a=rd(),b=rd();
         if(!a){
             que[i]=b;
         }else{
             int c=rd(),d=rd();
             lca[i][]=d;
             lq[i<<][]=b;lq[i<<][]=lqh[c];lqh[c]=i<<;
             lq[i<<|][]=c;lq[i<<|][]=lqh[b];lqh[b]=i<<|;
         }
     }
     dfs();
     for(i=;i<=M;i++){
         if(lca[i][]){
             // printf("!%d %d %d\n",lca[i][0],lq[i<<1][0],lq[i<<1|1][0]);
             add(dfn[lca[i][]][],-lca[i][]);
             if(fa[lca[i][]]) add(dfn[fa[lca[i][]]][],-lca[i][]);
             add(dfn[lq[i<<][]][],lca[i][]);
             add(dfn[lq[i<<|][]][],lca[i][]);
             // cout<<"mmm"<<endl;
         }else{
             printf("%lld\n",v[que[i]]+query(dfn[que[i]][])-query(dfn[que[i]][]-));
         }

     }
     return ;
 }