CSES - Shared codeLink to this code:
https://cses.fi/paste/1bf4b647a296d1da2fefaf/
/*
=============================================================================
/\ \ / /\ |\ /| |===========
/ \ \ / / \ | \ / | |
/ \ \ / / \ | \ / | |
/ \ | / \ | \ / | |===========
/--------\ | /--------\ | \ / | |
/ \ | / \ | \ / | |
/ \ | / \ | | | |===========
A A
AAAAAAAA AAA AAAA A A A A A A
A A A A A A A A A A A A A
A A AA A A A A A A A A A
A A A AA A A A A A A A
A AAA A A AAA AAA AAAAA
=============================================================================
*/
#include<bits/stdc++.h>
#define pb push_back
#define pf push_front
#define mp make_pair
#define F first
#define S second
#define pq priority_queue
#define ll long long int
#define pii pair<int,int>
#define endl '\n'
#define Orz ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define MAXN 200010
using namespace std;
//YeedragOrz
//8e7Orz
//jassOrz
//FHvirusOrz
//samOrz
//yungyaoOrz
//littlecubeOrz
//2qbingxuanOrz
//FoodSheepOrz
//ck_platypusOrz
//koyingOrz
//foxyyOrz
//peiganOrz
//jikuaiOrz
vector<int> edg[MAXN];int n,q,cnt=1,siz[MAXN]={},buil[MAXN]={},pr[MAXN]={},val[MAXN]={},dep[MAXN]={},in[MAXN]={},top[MAXN]={},seg[MAXN*4];
void modi(int cur,int l,int r,int pos,int val){
if(l>pos||r<pos)return;
if(l==r){
seg[cur]=val;return;
}
int mid=(l+r)/2;
modi(cur*2,l,mid,pos,val);modi(cur*2+1,mid+1,r,pos,val);
seg[cur]=max(seg[cur*2],seg[cur*2+1]);
}
void build(int cur,int l,int r){
if(l==r){
seg[cur]=buil[l];return;
}
int mid=(l+r)/2;
build(cur*2,l,mid);build(cur*2+1,mid+1,r);
seg[cur]=max(seg[cur*2],seg[cur*2+1]);
}
int query(int cur,int l,int r,int ql,int qr){
if(ql>r||qr<l)return 0;
if(ql<=l&&qr>=r)return seg[cur];
int mid=(l+r)/2;
return max(query(cur*2,l,mid,ql,qr),query(cur*2+1,mid+1,r,ql,qr));
}
void dfs_siz(int pos,int pre){
siz[pos]=1;
for(auto i:edg[pos]){
if(i!=pre){
dep[i]=dep[pos]+1;
dfs_siz(i,pos);
siz[pos]+=siz[i];pr[i]=pos;
}
}
}
void hld(int pos,int pre,int tp){
in[pos]=cnt++;top[pos]=tp;
int hchi=-1,hsiz=-1;
for(auto i:edg[pos]){
if(i!=pre)if(hsiz<siz[i]){
hsiz=siz[i];hchi=i;
}
}
if(hchi==-1)return;
hld(hchi,pos,tp);
for(auto i:edg[pos]){
if(i!=pre&&i!=hchi)hld(i,pos,i);
}
return;
}
int path(int a,int b){
int ans=0;
while(top[a]!=top[b]){
if(dep[top[a]]>dep[top[b]])swap(a,b);
ans=max(ans,query(1,1,n,in[top[b]],in[b]));
b=pr[top[b]];
}
if(dep[a]>dep[b])swap(a,b);
ans=max(ans,query(1,1,n,in[a],in[b]));
return ans;
}
int main(){
Orz
cin>>n>>q;for(int i=1;i<=n;i++)cin>>val[i];
for(int i=1;i<n;i++){
int a,b;cin>>a>>b;
edg[a].pb(b);edg[b].pb(a);
}
dep[1]=0;pr[1]=1;
dfs_siz(1,-1);
hld(1,-1,1);
for(int i=1;i<=n;i++)buil[in[i]]=val[i];
build(1,1,n);
while(q--){
int tmp;cin>>tmp;
if(tmp==1){
int s,x;cin>>s>>x;val[s]=x;modi(1,1,n,in[s],val[s]);
}else{
int a,b;cin>>a>>b;
cout<<path(a,b)<<" ";
}
}cout<<endl;
return 0;
}