RT,第九个点RE，是因为在判断连通前加了makeroot()的原因吗

#include <bits/stdc++.h>
using namespace std;
#define N 8000100
#define ll long long

inline ll read(){
	ll x = 0, s = 1;
	char c = getchar();
	while(!isdigit(c)){
		if(c == '-')s = -1;
		c = getchar();
	}
	while(isdigit(c)){
		x = x * 10 + c - '0';
		c = getchar();
	}
	return x * s;
}

ll fa[N], ch[N][2], rev[N], que[N], len, val[N];
ll sum[N], a[N];

ll is_lc(ll o){
	return ch[fa[o]][1] == o;
}

bool is_root(ll o){
	return !fa[o] || (ch[fa[o]][0] != o && ch[fa[o]][1] != o);
}

void pushup(ll o){
	sum[o] = sum[ch[o][0]] ^ sum[ch[o][1]] ^ a[o];
	return ;
}

void pushdown(ll o){
	if(rev[o]){
		swap(ch[o][0], ch[o][1]);
		if(ch[o][0]) rev[ch[o][0]] ^= 1;
		if(ch[o][1]) rev[ch[o][1]] ^= 1;
		rev[o] = 0;
	}
	return ;
}

void rotate(ll x){
	ll y = fa[x], z = fa[y], b = ch[y][0] == x ? ch[x][1] : ch[x][0];
	if(z && !is_root(y)) (ch[z][0] == y ? ch[z][0] : ch[z][1]) = x;
	fa[x] = z; fa[y] = x; 
	b ? fa[b] = y : 0;
	if(ch[y][0] == x) ch[x][1] = y, ch[y][0] = b;
	else ch[x][0] = y, ch[y][1] = b;
	pushup(y);
	pushup(x);
	return ;
}

void splay(ll x){
	ll i, y;
	que[len = 1] = x;
	for(y = x; !is_root(y); y = fa[y]) que[++len] = fa[y];
	for(i = len; i >= 1; i--) pushdown(que[i]);
	while(!is_root(x)){
		if(!is_root(fa[x])){
			if(is_lc(x) == is_lc(fa[x])) rotate(fa[x]);
			else rotate(x);
		}
		rotate(x);
	}
	pushup(x);
	return ;
}

void access(ll x){
	for(ll y = 0; x; y = x, x = fa[x]){
		splay(x);
		ch[x][1] = y;
		if(y) fa[y] = x;
		pushup(x);
	}
	return ;
}
inline void make_root(ll x){
	access(x);
	splay(x);
	rev[x] ^= 1;
	return ;
}

ll find_root(ll x){
	make_root(x);
	access(x);
	splay(x);
	while(ch[x][0]) x = ch[x][0]; 
	splay(x);
	return x;
}

inline void link(ll x, ll y){
	make_root(x);
	fa[x] = y;
	return ;
}

inline void split(ll x, ll y){
	make_root(x);
	access(y);
	splay(y);
	return ;
}

inline void cut(ll x, ll y){
	split(x, y);
	ch[y][0] = 0;
	fa[x] = 0;
	pushup(y);
	return ;
}

inline ll query(ll x, ll y){
	split(x, y);
	return sum[y];
}

inline void change(ll x, ll w){
	splay(x);
	a[x] = w;
	pushup(x);
	return ;
}

inline bool is_link(ll x, ll y){
	make_root(x); make_root(y);
	return find_root(x) == find_root(y);
}

int main(){
	freopen("测试.txt", "r", stdin);
	freopen("out.txt", "w", stdout);
	ll n = read(), q = read();
	for(ll i = 1;i <= n; i++) a[i] = read();
	while(q--){
		ll flag = read();
		ll x = read(), y = read();
		switch(flag){
			case 0:
				printf("%lld\n", query(x, y));
				break;
			case 1:
				if(!is_link(x, y)) link(x, y);
				break;
			case 2: 
				if(is_link(x, y)) cut(x, y);
				break;
			case 3:
				change(x, y);
				break;
		}
	}
	return 0;
}