也许是目前最简洁的指针 LCT

甚至比非指针 LCT 精简了很多细节，不需要记忆那一堆操作。

#include <cstdio>
#include <algorithm>
using namespace std;
struct T
{
    T *f, *c[2];
    int v, q;
    bool b;
    T(int v) : f(0), c{0, 0}, v(v), q(v), b(0) {}
    bool g() { return f->c[1] == this; }
    bool r() { return !f || f->c[0] != this && f->c[1] != this; }
    void u()
    {
        q = v;
        if (c[0])
            q ^= c[0]->q;
        if (c[1])
            q ^= c[1]->q;
    }
    void o()
    {
        b ^= 1;
        swap(c[0], c[1]);
    }
    void d()
    {
        if (b)
        {
            if (c[0])
                c[0]->o();
            if (c[1])
                c[1]->o();
            b = 0;
        }
    }
} *x, *y, *p, *r[100050];
void R(T *x)
{
    T *y = x->f, *z = y->f;
    if (!y->r())
        z->c[y->g()] = x;
    bool k = x->g();
    if (y->c[k] = x->c[!k])
        y->c[k]->f = y;
    ((x->c[!k] = y)->f = x)->f = z;
    y->u();
}
void U(T *x)
{
    if (!x->r())
        U(x->f);
    x->d();
}
void S(T *x)
{
    U(x);
    for (; !x->r(); R(x))
        if (!x->f->r())
            R(x->g() == x->f->g() ? x->f : x);
}
T *A(T *x)
{
    T *p = 0;
    for (; x; p = x, x = x->f)
        S(x), x->c[1] = p, x->u();
    return p;
}
T *F(T *x)
{
    for (x = A(x); x->c[0]; x = x->c[0])
        x->d();
    return S(x), x;
}
int n, m;
int main()
{
    scanf("%d%d", &n, &m);
    for (int i = 1, x; i <= n; ++i)
        scanf("%d", &x), r[i] = new T(x);
    for (int i = 0, o, u, v; i < m; ++i)
    {
        scanf("%d%d%d", &o, &u, &v);
        x = r[u];
        if (o != 3)
            y = r[v];
        switch (o)
        {
        case 0:
            A(x)->o();
            printf("%d\n", A(y)->q);
            break;
        case 1:
            (p = A(x))->o();
            if (F(y) != x)
                p->f = y;
            break;
        case 2:
            A(x)->o();
            if (F(y) == x && x->c[1] == y && !y->c[0])
                x->c[1] = y->f = 0;
            break;
        case 3:
            x->v = v;
            S(x);
            break;
        }
    }
    return 0;
}

很多地方其实不必判空。

很多地方其实不必 Splay。

Rotate 里可以少 Push up 一次。

Access 带返回值可以精简很多操作。