BZOJ3730 震波 [点分治][点分序]

重来都不知道有个东西叫做点分序。。。考试多半GG，还以为可以用启发式合并平衡树乱搞，哎我还是太naive了，这道题就是依据点分治的顺序来进行操作，一道经典题。

#include<cstdio>#include<vector>#include<cstring>#include<iostream>#include<algorithm>#define N 200010#define M 20000010using namespace std;int n,m,cnt,SZ,MX,tot;int val[N],head[N],vis[N],rt[N],p[N],prt[N],dep[N],s[N],lastans,tal;int fa[N][25];int *G[N],*P[N];int por[M],por1[M];struct edge{    int to,nxt;}E[N<<1];inline char readc(){    static char buf[100000],*p1=buf,*p2=buf;    return p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++;}inline void read(int &x){    char c=readc(); x=0;    for(;c>'9'||c<'0';c=readc());for(;c>='0'&&c<='9';x=x*10+c-'0',c=readc());}inline void addedge(int x,int y){    E[++cnt].to=y,E[cnt].nxt=head[x],head[x]=cnt;    E[++cnt].to=x,E[cnt].nxt=head[y],head[y]=cnt;}int dfs(int x,int f,int d){    int ret=1;    for(register int v,i=head[x];i;i=E[i].nxt)        if(v=E[i].to,v!=f&&!vis[v])ret+=dfs(v,x,d+1);    return ret;}int dfsroot(int x,int f,int &k){    int s=1,mx=0;    for(register int v,i=head[x];i;i=E[i].nxt)        if(v=E[i].to,v!=f&&!vis[v]){            int w=dfsroot(v,x,k);            if(mx<w)mx=w;            s+=w;        }    if(mx<SZ-s)mx=SZ-s;    if(mx<MX)MX=mx,k=x;    return s;}void dfsdiv(int x,int f){    SZ=dfs(x,0,0),MX=1<<30;int k;    dfsroot(x,0,k),p[k]=f;    vis[k]=1,s[k]=SZ+2;    for(register int i=head[k];i;i=E[i].nxt)        if(!vis[E[i].to])dfsdiv(E[i].to,k);}void dfss(int x,int f){    dep[x]=dep[f]+1,fa[x][0]=f;    for(register int i=1;i<=16;i++)fa[x][i]=fa[fa[x][i-1]][i-1];    for(int i=head[x];i;i=E[i].nxt)        if(E[i].to!=f)dfss(E[i].to,x);}inline int LCA(int x,int y){    if(dep[x]<dep[y])return LCA(y,x);    for(register int i=16;~i;i--)        if(dep[fa[x][i]]>=dep[y])x=fa[x][i];    if(x==y)return x;    for(register int i=16;~i;i--)        if(fa[x][i]!=fa[y][i])x=fa[x][i],y=fa[y][i];    return fa[x][0];}inline int dis(int x,int y){    return dep[x]+dep[y]-2*dep[LCA(x,y)];}inline int query(int *A,int x){    int ret=0;    for(;x>0;x-=x&-x)ret+=A[x];    return ret;}inline int query(int* A,int r,int t){    r=min(r+1,t);    return query(A,r);}inline int Query(int x,int y){    int ret=query(G[x],y,s[x]);    for(register int i=x;p[i];i=p[i]){        int d=dis(x,p[i]);        if(d>y)continue;        ret+=query(G[p[i]],y-d,s[p[i]])-query(P[i],y-d,s[i]);    }    return ret;}inline void insert(int *A,int x,int y,int t){    x=min(x+1,t);    if(x==0)return;    for(;x<=t;x+=x&-x)A[x]+=y;}inline void add(int x,int y){    insert(G[x],0,y,s[x]);    for(register int i=x;p[i];i=p[i]){        int d=dis(x,p[i]);        insert(P[i],d,y,s[i]),insert(G[p[i]],d,y,s[p[i]]);    }}int main(){    read(n),read(m);    for(register int i=1;i<=n;i++)read(val[i]);    for(register int x,y,i=1;i<n;i++)        read(x),read(y),addedge(x,y);    dfsdiv(1,0),dfss(1,0);    for(register int i=1;i<=n;i++)        G[i]=por+tal,P[i]=por1+tal,tal+=s[i]+2;    for(register int i=1;i<=n;i++)add(i,val[i]);    for(register int op,x,y,i=1;i<=m;i++){        read(op),read(x),read(y);        x^=lastans;y^=lastans;        if(op==0)printf("%d\n",lastans=Query(x,y));        else add(x,y-val[x]),val[x]=y;    }    return 0;}