用题解和讨论里的数据生成器对拍没找到错误

（用分块写的

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<set>
#include<cstring>
#include<bitset>
#define inf 0x7f7f7f7f
#define X 20005
#define ll long long
#define MOD 998244353
#define maxn 100050 
using namespace std;
inline int Max(int a,int b) {return a>b?a:b;}
inline int Min(int a,int b) {return a<b?a:b;}
inline void Swap(int &a,int &b) {a=a^b;b=a^b;a=a^b;}
inline int scan()
{
    register int x=0,f=0;
	register char c=getchar();
    while(c<'0') f|=(c=='-'),c=getchar();
    while(c>='0') x=(x<<1)+(x<<3)+(c&15),c=getchar();
    return f?-x:x;
}
inline void print(int x)
{
    if(x/10) print(x/10); 
    putchar(x%10+48);
}
int edge_w[210000],edge_Next[210000],edge_to[210000];
int head[100005],total;
inline void add_edge(int u,int v)
{
    edge_to[++total]=v;
    edge_Next[total]=head[u];
    head[u]=total;
}
int size[100005],son[100005],top[100005],father[100005],deep[100005];
void dfs_first(int s,int fa)
{
	size[s]=1;
	father[s]=fa;
	deep[s]=deep[fa]+1;
	for (register int e=head[s],Next;e;e=edge_Next[e])
	{
		Next=edge_to[e];
		Next!=fa?(dfs_first(Next,s),size[s]+=size[Next],(size[Next]>size[son[s]]?son[s]=Next:0)):0;
	}
	return ;
}
int pointnum[100005],tree_to_line[100005],line_to_tree[100005],idcnt;
void dfs_second(int s,int Top)
{
	idcnt++;
	line_to_tree[idcnt]=s;
	tree_to_line[s]=idcnt;
	top[s]=Top;
	if (son[s]) dfs_second(son[s],Top);
	register int Next;
	for (register int e=head[s];e;e=edge_Next[e])
	{
		Next=edge_to[e];
		(Next!=father[s]&&Next!=son[s])?dfs_second(Next,Next),0:0;
	}
	return ;
}
set<int>check;
int n,m,q,k,x,y,s,p;
int block;
int left[5000],right[5000],pos[100005];
int sumblock[5000],date[100005],tag[5000];
inline void build()
{
	block=sqrt(n);
	for (int i=1;i<=block;i++)
	{
		tag[i]=inf;
		left[i]=(i-1)*block+1;
		right[i]=block*i;
	}
	right[block]=n;
	for (int i=1;i<=n;i++)
		date[i]=pointnum[line_to_tree[i]];
	for (int i=1;i<=block;i++)
	{
		check.clear();
		for (int j=left[i];j<=right[i];j++)
		{
			check.insert(date[j]);
			pos[j]=i;
		}
		sumblock[i]=check.size();
	}
}
inline void change(int l,int r,int cag)
{
	for (int i=pos[l];i<=pos[r];i++)
	{
		if (l<=left[i]&&right[i]<=r)
		{
			tag[i]=cag;
			date[left[i]]=cag;
			date[right[i]]=cag;
			sumblock[i]=1;
		}
		else
		{
			if (tag[i]!=inf)
			{
				for (int j=left[i];j<=right[i];j++)
					date[j]=tag[i];
				for (int j=Max(left[i],l);j<=Min(right[i],r);j++)
					date[j]=cag;
				if (cag==tag[i]) sumblock[i]=1;
				else sumblock[i]=2;
				tag[i]=inf;
				continue;
			}
			check.clear();
			for (int j=Max(left[i],l);j<=Min(right[i],r);j++)
				date[j]=cag;
			for (int j=left[i];j<=right[i];j++)
				check.insert(date[j]);
			sumblock[i]=check.size();
		}
	}
}
int lcolor,rcolor;
inline int query(int l,int r)
{
	int res=0,sid=pos[l],eid=pos[r];
	if (sid==eid)
	{
		if (tag[sid]!=inf) return 1;
		check.clear();
		for (int i=l;i<=r;i++)
			check.insert(date[i]);
		res=check.size();
		return res;
	}
	if (tag[sid]!=inf) res=1;
	else
	{
		check.clear();
		for (int i=l;i<=right[sid];i++)
			check.insert(date[i]);
		res+=check.size();
	}
	for (int i=sid+1;i<eid;i++)
	{
		res+=sumblock[i];
		if (date[left[i]-1]==date[left[i]]) res--;
	}
	if (tag[eid]!=inf)
		for (int i=left[eid];i<=right[eid];i++)
			date[i]=tag[eid];
	if (right[eid]==r)
	{
		res+=sumblock[eid];
		if (date[left[eid]-1]==date[left[eid]]) res--;
		return res;
	}
	check.clear();
	for (int i=left[eid];i<=r;i++)
		check.insert(date[i]);
	res+=check.size();
	if (date[left[eid]-1]==date[left[eid]]) res--;
	return res;
}
inline int checktopcolor(int x)
{
	int belong=pos[tree_to_line[x]];
	if (tag[belong]!=inf) return tag[belong];
	return date[tree_to_line[x]];
}
inline void change_xtoy(int x,int y,int cag)
{
	while (top[x]!=top[y])
	{
		if (deep[top[x]]<deep[top[y]]) Swap(x,y);
		change(tree_to_line[top[x]],tree_to_line[x],cag);
		x=father[top[x]];
	}
	if (tree_to_line[x]>tree_to_line[y]) Swap(x,y);
	change(tree_to_line[x],tree_to_line[y],cag);
	return ;
}
inline int query_x_to_y(int x,int y)
{
	int ans=0;
	while (top[x]!=top[y])
	{
		if (deep[top[x]]<deep[top[y]]) Swap(x,y);
		ans+=query(tree_to_line[top[x]],tree_to_line[x]);
		if (checktopcolor(top[x])==checktopcolor(father[top[x]])) ans--;
		x=father[top[x]];
	}
	if (tree_to_line[x]>tree_to_line[y]) Swap(x,y);
	ans+=query(tree_to_line[x],tree_to_line[y]);
	return ans;
}
int cag;
int main()
{
	n=scan();m=scan();s=1;
	for (int i=1;i<=n;i++) pointnum[i]=scan();
	for (int i=1;i<n;i++)
	{
		x=scan();y=scan();
		add_edge(x,y);
		add_edge(y,x);
	}
	dfs_first(s,0);
	dfs_second(s,s);
	build();
	char order;
	while (m--)
	{
		order=getchar();
		while (order!='C'&&order!='Q') order=getchar();
		if (order=='C')
		{
			x=scan();y=scan();cag=scan();
			change_xtoy(x,y,cag);
		}
		else
		{
			x=scan();y=scan();
			print(query_x_to_y(x,y));
			putchar('\n');
		}
	}
	return 0;
}