luogu P3690【模板】Link Cut Tree（动态树）

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#include<climits>
#include<stack>
#include<vector>
#include<queue>
#include<set>
#include<bitset>
#include<map>
//#include<regex>
#include<cstdio>
#include <iomanip>
#pragma GCC optimize(2)
#define up(i,a,b)  for(int i=a;i<b;i++)
#define dw(i,a,b)  for(int i=a;i>b;i--)
#define upd(i,a,b) for(int i=a;i<=b;i++)
#define dwd(i,a,b) for(int i=a;i>=b;i--)
//#define local
typedef long long ll;
typedef unsigned long long ull;
const double esp = 1e-6;
const double pi = acos(-1.0);
const int INF = 0x3f3f3f3f;
const int inf = 1e9;
using namespace std;
ll read()
{
	char ch = getchar(); ll x = 0, f = 1;
	while (ch<'0' || ch>'9') { if (ch == '-')f = -1; ch = getchar(); }
	while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); }
	return x * f;
}
typedef pair<int, int> pir;
#define lson l,mid,root<<1
#define rson mid+1,r,root<<1|1
#define lrt root<<1
#define rrt root<<1|1
const int N = 3e5 + 10;
int n, m;
struct node {
	int ch[2], fa, lazy, val;
}tree[N];
int val[N];
int ident(int rt,int fa) {
	return tree[fa].ch[1] == rt;
}
void connect(int rt, int fa,int son)
{
	tree[rt].fa = fa;
	tree[fa].ch[son] = rt;
}
bool isroot(int rt)
{
	int f = tree[rt].fa;
	return tree[f].ch[1] != rt && tree[f].ch[0] != rt;
}
void pushup(int rt) {
	int ls = tree[rt].ch[0];
	int rs = tree[rt].ch[1];
	tree[rt].val = tree[ls].val^tree[rs].val ^ val[rt];
}
void rev(int x)
{
	swap(tree[x].ch[0], tree[x].ch[1]);
	tree[x].lazy ^= 1;
}
void pushdown(int rt)
{
	if (tree[rt].lazy)
	{
		if (tree[rt].ch[0])rev(tree[rt].ch[0]);
		if (tree[rt].ch[1])rev(tree[rt].ch[1]);
		tree[rt].lazy = 0;
	}
}
void pushall(int rt)
{
	if (!isroot(rt))pushall(tree[rt].fa);
	pushdown(rt);
}
void rotate(int rt)
{
	int f = tree[rt].fa; int ff = tree[f].fa; int k = ident(rt, f);
	connect(tree[rt].ch[k ^ 1], f, k);
	tree[rt].fa = ff;
	if (!isroot(f))tree[ff].ch[ident(f, ff)] = rt;
	connect(f, rt, k ^ 1);
	pushup(f); pushup(rt);
}
void splay(int x)
{
	pushall(x);
	while (!isroot(x))
	{
		int f = tree[x].fa; int ff = tree[f].fa;
		if (!isroot(f))
			ident(f, ff) ^ ident(x, f) ? rotate(x) : rotate(f);
		rotate(x);
	}
}
void access(int x)
{
	for (int y = 0; x; x = tree[x].fa)
	{
		splay(x);
		tree[x].ch[1] = y;
		pushup(x);        
		y = x;
	}
}
void makeroot(int x)
{
	access(x); splay(x); rev(x);
}
int findroot(int x)
{
	access(x); splay(x);
	while (tree[x].ch[0]) {
		pushdown(x);
		x = tree[x].ch[0];
	}
	splay(x);
	return x;
}
void link(int x,int y)
{
	makeroot(x);
	if (findroot(y) != x)tree[x].fa = y;
}
void cut(int x, int y)
{
	makeroot(x);
	if (findroot(y) != x || tree[y].fa != x || tree[y].ch[0])return;
	tree[y].fa = tree[x].ch[1] = 0;
	pushup(x);
}
void split(int x, int y)
{
	makeroot(x);
	access(y);
	splay(y);
}
int main()
{
#ifdef local
	freopen("D:\++\P3690_9.in", "r", stdin);
	freopen("D:\++\P3369_2.out", "w", stdout);
#endif // 

	n = read(), m = read();
	upd(i, 1, n)tree[i].val = read(), val[i] = tree[i].val;
	int op, xx, yy;
	while (m--)
	{
		op = read();
		xx = read(), yy = read();
		if (op == 0)
		{
			split(xx, yy);
			printf("%d\n", tree[yy].val);
		}
		else if (op == 1)
		{
			link(xx, yy);
		}
		else if (op == 2)
		{
			cut(xx, yy);
		}
		else if (op == 3)
		{
			splay(xx);
			val[xx] = yy;
			pushup(xx);
		}
	}
	return 0;
}