BZOJ 4129: Haruna’s Breakfast [树上莫队 分块]

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
const int N=5e4+5;
inline int read(){
char c=getchar();int x=0,f=1;
while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
return x*f;
}

int n,Q,a
,t
,op,x,y;
struct edge{int v,ne;} e[N<<1];
int cnt,h
;
inline void ins(int u,int v){
e[++cnt]=(edge){v,h[u]}; h[u]=cnt;
e[++cnt]=(edge){u,h[v]}; h[v]=cnt;
}
int block, pos
, m, st
, top;
int fa
[18], deep
;
void dfs(int u){
for(int i=1; (1<<i)<=deep[u]; i++)
fa[u][i]=fa[ fa[u][i-1] ][i-1];
int bot=top;
for(int i=h[u];i;i=e[i].ne) if(e[i].v!=fa[u][0]){
fa[e[i].v][0]=u; deep[e[i].v]=deep[u]+1;
dfs(e[i].v);
if(top-bot>=block){
m++;
while(top!=bot) pos[st[top--]]=m;
}
}
st[++top]=u;
}
inline int lca(int x,int y){
if(deep[x]<deep[y]) swap(x, y);
int bin=deep[x]-deep[y];
for(int i=0;i<17;i++) if((1<<i)&bin) x=fa[x][i];
if(x==y) return x;
for(int i=16;i>=0;i--)
if(fa[x][i]!=fa[y][i]) x=fa[x][i], y=fa[y][i];
return x==y ? x : fa[x][0];
}

struct cmeow{int u, next, last;}cq
;
struct meow{
int u, v, tim, id;
bool operator <(const meow &a) const {
return pos[u]==pos[a.u] ? (pos[v]==pos[a.v] ? tim<a.tim : pos[v]<pos[a.v]) : pos[u]<pos[a.u];
}
}q
;
int p, tim, u, v, cur, ans
, vis
;

struct Block{
int n,pos
,m,block;
struct _blo{int l,r;} b[350];
void ini(){
block=sqrt(n); m=(n-1)/block+1;
for(int i=1;i<=n;i++) pos[i]=(i-1)/block+1;
for(int i=1;i<=m;i++) b[i].l=(i-1)*block+1, b[i].r=i*block;
b[m].r=n;
}
int cou
, sum[350];
inline void add(int v) { if(v<=n) sum[pos[v]]+= (++cou[v])==1; }
inline void del(int v) { if(v<=n) sum[pos[v]]-= (--cou[v])==0; }
inline int mex(){
for(int i=1;i<=m;i++) if(sum[i] != b[i].r-b[i].l+1)
for(int j=b[i].l; j<=b[i].r; j++) if(!cou[j]) return j;
return -1;
}
}B;
inline void cha(int u,int d){
if(vis[u]) B.del(a[u]), B.add(d);
a[u]=d;
}
inline void Xor(int u){
if(vis[u]) B.del(a[u]), vis[u]=0;
else B.add(a[u]), vis[u]=1;
}
inline void move(int x,int y){
if(deep[x]<deep[y]) swap(x, y);
while(deep[x]>deep[y]) Xor(x), x=fa[x][0];
while(x!=y) Xor(x), Xor(y), x=fa[x][0], y=fa[y][0];
}

void modui(){
u=v=1;
for(int i=1;i<=p;i++){
while(cur<q[i].tim) cur++, cha(cq[cur].u, cq[cur].next);
while(cur>q[i].tim) cha(cq[cur].u, cq[cur].last), cur--;
if(u!=q[i].u) move(u, q[i].u), u=q[i].u;
if(v!=q[i].v) move(v, q[i].v), v=q[i].v;
int anc=lca(u, v);
Xor(anc); ans[q[i].id]=B.mex()-1; Xor(anc);
}
}

int main(){
freopen("in","r",stdin);
n=read(); Q=read();
for(int i=1;i<=n;i++) a[i]=t[i]=read()+1;
for(int i=1;i<n ;i++) ins(read(), read() );
block=pow(n, 0.45);
dfs(1);
while(top) pos[st[top--]]=m;
for(int i=1;i<=Q;i++){
op=read(); x=read(); y=read();
if(op) p++, q[p]=(meow){x, y, tim, p};
else tim++, cq[tim]=(cmeow){x, y+1, t[x]}, t[x]=y+1;
}

B.n = n+1; B.ini();
sort(q+1, q+1+p);
modui();
for(int i=1;i<=p;i++) printf("%d\n",ans[i]);
}