BZOJ 4129 Haruna’s Breakfast

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
#include<cmath>
using namespace std;
const int maxn = 505000;
vector<int> f[maxn],g[maxn];
int val[maxn],deep[maxn],fa[maxn],son[maxn],top[maxn],sz[maxn],dfn[maxn],q[maxn],pre[maxn];
int pos[maxn],res[maxn],num[maxn],belong[maxn],n,m,x,y,blo,blonum,dfs_clock,Top,ans;
struct oper{
int x,y,id,op,t;
}T[maxn];
struct change{
int x,y,t,pre,id;
}F[maxn];
bool vis[maxn];
bool operator < (oper a,oper b){
if(belong[a.x]==belong[b.x]&&belong[a.y]==belong[b.y]) return a.t<b.t;
else if(belong[a.x]==belong[b.x]) return belong[a.y]<belong[b.y];
else return belong[a.x]<belong[b.x];
}
int dfs1(int x,int fath,int dep){
int size=0;
dfn[x]=++dfs_clock;deep[x]=dep;
sz[x]=1;son[x]=0;fa[x]=fath;
for(int i=0;i<f[x].size();i++){
int v=f[x][i];
if(v==fath) continue;
size+=dfs1(v,x,dep+1);
sz[x]+=sz[v];
if(size>=blo){
blonum++;
for(int k=1;k<=size;k++)
belong[q[Top--]]=blonum;
size=0;
}
if(sz[son[x]]<sz[v]) son[x]=v;
}
q[++Top]=x;
return size+1;
}
void dfs2(int x,int tp){
top[x]=tp;
if(son[x]) dfs2(son[x],tp);
for(int i=0;i<f[x].size();i++){
int v=f[x][i];
if(v==fa[x]||v==son[x]) continue;
dfs2(v,v);
}
}
int lca(int a,int b){
while(top[a]!=top[b]){
if(deep[top[a]]<deep[top[b]]) swap(a,b);
a=fa[top[a]];
}
return deep[a]>deep[b] ? b : a;
}
void reverse(int x){
if(vis[x]){
if(val[x]>maxn) return;
num[val[x]]--;if(!num[val[x]]){
if(ans>val[x]) ans=val[x];
}
}
else{
if(val[x]>maxn) return;
num[val[x]]++;if(ans==val[x]){
while(num[ans]) ans++;
}
}
vis[x]^=1;
}
void change(int x,int y){
if(vis[x]){
reverse(x);val[x]=y;reverse(x);
}else val[x]=y;
}
void solve(int x,int y){
while(x!=y){
if(deep[x]>deep[y]) reverse(x),x=fa[x];
else reverse(y),y=fa[y];
}
}
int main()
{
scanf("%d%d",&n,&m);
blo=pow(n,2.0/3)*0.5;
for(int i=1;i<=n;i++) scanf("%d",&val[i]),pre[i]=val[i];
for(int i=1;i<n;i++){
scanf("%d%d",&x,&y);
f[x].push_back(y);
f[y].push_back(x);
}
dfs1(1,1,0);
dfs2(1,1);
while(Top) belong [q[Top--]]=blonum;
int c1=0,c2=0,typ;
for(int i=1;i<=m;i++){
scanf("%d%d%d",&typ,&x,&y);
if(!typ){
c1++;
F[c1].x=x;F[c1].y=y;F[c1].pre=pre[x];pre[x]=y;
}else{
c2++;
if(dfn[x]>dfn[y]) swap(x,y);
T[c2].x=x;T[c2].y=y;T[c2].id=c2;T[c2].t=c1;
}
}
sort(T+1,T+1+c2);
for(int i=1;i<=T[1].t;i++) change(F[i].x,F[i].y);
int t=lca(T[1].x,T[1].y);
solve(T[1].x,T[1].y);
reverse(t);res[T[1].id]=ans;reverse(t);
//  cout<<T[1].id<<endl;
//  for(int j=1;j<=10;j++) cout<<vis[j]<<" ";
//  cout<<endl;
for(int i=2;i<=c2;i++)
{
//      cout<<T[i].id<<" "<<i<<" "<<T[i].x<<" "<<T[i].y<<" "<<T[i].t<<endl;
for(int j=T[i-1].t+1;j<=T[i].t;j++)
change(F[j].x,F[j].y);
for(int j=T[i-1].t;j>T[i].t;j--)
change(F[j].x,F[j].pre);
solve(T[i-1].x,T[i].x);solve(T[i-1].y,T[i].y);
//      cout<<T[i-1].y<<" "<<T[i].y<<" "<<deep[T[i-1].y]<<" "<<deep[T[i].y]<<endl;
//      for(int j=1;j<=10;j++) cout<<vis[j]<<" ";
//      cout<<endl;

int t=lca(T[i].x,T[i].y);
reverse(t);res[T[i].id]=ans;reverse(t);

}
for(int i=1;i<=c2;i++)
printf("%d\n",res[i]);
return 0;
}