测了多组大数据，在几千或几万行处突然输出-1，不知道哪里出错

#include<bits/stdc++.h>
#define lx x<<1
#define rx x<<1|1
#define int long long
using namespace std;
int tree[200001],minn[200001];
int n,q,cnt,dfn;
int siz[100001],id[100001],deep[100001],head[100001],top[100001],fa[100001],son[100001];
int w[100001],w1[100001];
struct Edge {int to,nex;}edge[100001];
void pushup(int x)
{
    tree[x]=tree[lx]+tree[rx];
    minn[x]=max(minn[lx],minn[rx]);
}
void build(int x,int l,int r)
{
    if(l==r)
    {
        tree[x]=w1[l];
        minn[x]=w1[l];
        return;
    }
    int mid=(l+r)>>1;
    build(lx,l,mid);
    build(rx,mid+1,r);
    pushup(x);
}
void update(int ll,int x,int l,int r,int z)
{
    if(l==r&&l==ll)
    {
           minn[x]=z;
           tree[x]=z;
           return;
    }
    int mid=(l+r)>>1;
    if(ll<=mid) update(ll,lx,l,mid,z);
    if(ll>mid) update(ll,rx,mid+1,r,z);
    pushup(x);
}
int query(int ll,int rr,int x,int l,int r)
{
    if(ll<=l&&r<=rr)
    {
        return tree[x];
    }
    int res=0;
    int mid=(l+r)>>1;
    if(ll<=mid) res+=query(ll,rr,lx,l,mid);
    if(rr>mid) res+=query(ll,rr,rx,mid+1,r);
    return res;
}
int querymin(int ll,int rr,int x,int l,int r)
{
    if(ll<=l&&r<=rr)
    {
        return minn[x];
    }
    int small=-1;
    int mid=(l+r)>>1;
    if(ll<=mid) small=max(querymin(ll,rr,lx,l,mid),small);
    if(rr>mid) small=max(querymin(ll,rr,rx,mid+1,r),small);
    return small;
}
void addedge(int u,int v)
{
    edge[++cnt].to=v;
    edge[cnt].nex=head[u];
    head[u]=cnt;
}
void dfs(int x,int fath)
{
    siz[x]=1;
    deep[x]=deep[fath]+1;
    fa[x]=fath;
    for(int i=head[x];i;i=edge[i].nex)
    {
        int v=edge[i].to;
        if(v==fath) continue;
        dfs(v,x);
        siz[x]+=siz[v];
        if(!son[x]||siz[son[x]]<siz[v]) son[x]=v;
    }
}
void dfs1(int x,int topx)
{
      id[x]=++dfn;
      top[x]=topx;
      w1[dfn]=w[x];
      if(!son[x]) return;
      dfs1(son[x],topx);
      for(int i=head[x];i;i=edge[i].nex)
      {
          int v=edge[i].to;
          if(v!=fa[x]&&v!=son[x])
          {
              dfs1(v,v);
          }
      }
}
int query_range(int x,int y)
{
    int res=0;
    while(top[x]!=top[y])
    {
        if(deep[top[x]]<deep[top[y]]) swap(x,y);
        res+=query(id[top[x]],id[x],1,1,n);
        x=fa[top[x]];
    }
    if(deep[x]>deep[y]) swap(x,y);
    res+=query(id[x],id[y],1,1,n);
    return res;
}
int querym(int x,int y)
{
    int res=-1;
    while(top[x]!=top[y])
    {
        if(deep[top[x]]<deep[top[y]]) swap(x,y);
        res=max(querymin(id[top[x]],id[x],1,1,n),res);
        x=fa[top[x]];
    }
    if(deep[x]>deep[y]) swap(x,y);
    res=max(querymin(id[x],id[y],1,1,n),res);
    return res;
}
signed main()
{
    //freopen("count2.in","r",stdin);
    //freopen("count.out","w",stdout);
    cin>>n;
    for(int i=1;i<n;i++)
    {
        int u,v;
        scanf("%lld%lld",&u,&v);
        addedge(u,v);
        addedge(v,u);
    }
    for(int i=1;i<=n;i++)
    {
        int x;
        scanf("%lld",&x);
        w[i]=x;
    }
    dfs(1,1);
    dfs1(1,1);
    build(1,1,n);
    cin>>q;
    while(q--)
    {
        string s;
        cin>>s;
        int x,y;
        scanf("%lld%lld",&x,&y);
        //cout<<x<<' '<<y<<endl;
        if(s=="QMAX")
        {
            printf("%lld\n",querym(x,y));
            //cout<<querymax(x,y)<<endl;
        }
        if(s=="QSUM")
        {
            printf("%lld\n",query_range(x,y));
        }
        if(s=="CHANGE")
        {
            update(id[x],1,1,n,y);
        }
    }
    return 0;
}