rt，WA光了QAQ

求调 orz

#include <iostream>
#include <algorithm>

using namespace std;
const int N = 1e5 + 5;

#define left LEFT
#define right RIGHT

#define lc ch[x][0]
#define rc ch[x][1]

int ch[N][2], fa[N];
int cnt[N], left[N], right[N], val[N];
bool rev[N], cov[N];

inline void pushup(int x) {
	left[x] = lc ? left[lc] : val[x];
	right[x] = rc ? right[rc] : val[x];
	if (lc && rc) {
		cnt[x] = cnt[lc] + cnt[rc] + 1;
		if (left[rc] == val[x]) cnt[x]--;
		if (right[lc] == val[x]) cnt[x]--;
	} else if (lc)
		cnt[x] = cnt[lc] + (val[x] != right[lc]);
	else if (rc)
		cnt[x] = cnt[rc] + (val[x] != left[rc]);
	else cnt[x] = 1;
}

inline void setRev(int x) {
	swap(lc, rc), swap(left[x], right[x]), rev[x] ^= 1;
}
inline void setCov(int x, int v) {
	cnt[x] = 1, left[x] = right[x] = val[x] = v, cov[x] = 1;
}
inline void pushdown(int x) {
	if (cov[x]) {
		if (lc) setCov(lc, val[x]);
		if (rc) setCov(rc, val[x]);
		cov[x] = rev[x] = 0;
	}
	if (rev[x]) {
		if (lc) setRev(lc);
		if (rc) setRev(rc);
		rev[x] = 0;
	}
}

inline bool isRoot(int x) {
	return x != ch[fa[x]][0] && x != ch[fa[x]][1];
}
inline void rotate(int x) {
	int y = fa[x], z = fa[y];
	int k = ch[y][1] == x, w = ch[x][!k];
	if (!isRoot(y)) ch[z][ch[z][1] == y] = x;
	ch[x][!k] = y, ch[y][k] = w;
	if (w) fa[w] = y;
	fa[y] = x, fa[x] = z; pushup(y);
}

inline int getch(int x) {
	return x == ch[fa[x]][1];
}
int stk[N], top = 0;
void pushdownAll(int x) {
	int y = x; stk[top = 1] = y;
	while (!isRoot(y)) stk[++top] = y = fa[y];
	while (top) pushdown(stk[top--]);
}
inline void splay(int x) {
	pushdownAll(x);
	for (register int y = fa[x]; !isRoot(x); rotate(x), y = fa[x])
		if (!isRoot(y)) rotate(getch(x) != getch(y) ? x : y);
	pushup(x);
}

inline void access(int x) {
	for (register int y = 0; x; x = fa[y = x])
		splay(x), rc = y, pushup(x);
}
inline void makeRoot(int x) {
	access(x), splay(x), setRev(x);
}
inline void link(int x, int y) {
	makeRoot(x), fa[x] = y;
}
inline void split(int x, int y) {
	makeRoot(x), access(y), splay(y);
}

signed main() {
	ios::sync_with_stdio(false);
	int n, q;
	
	cin >> n >> q;
	for (register int i = 1; i <= n; i++) {
		cin >> val[i];
		left[i] = right[i] = val[i];
		cnt[i] = 1;
	}
	
	for (register int u, v, i = 1; i < n; i++)
		cin >> u >> v, link(u, v);
	
	for (; q; --q) {
		char cmd; int x, y, v;
		cin >> cmd >> x >> y;
		split(x, y);
		if (cmd == 'Q') cout << cnt[y] << endl;
		else cin >> v, setCov(y, v);
	}
}