Los Valley - P4567 - text editor - no spin Treap

https://www.luogu.org/problem/P4567
proved no spin Treap is not impossible will be faster than Splay?

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ls(p) ch[p][0]
#define rs(p) ch[p][1]

const int MAXN = 2400000 + 5;
char val[MAXN];
int ch[MAXN][2], rnd[MAXN], siz[MAXN], tot, root;

int cur;
bool rev[MAXN];

void Init() {
    root = 0, tot = 0;
}

inline void PushUp(int p) {
    siz[p] = siz[ls(p)] + siz[rs(p)] + 1;
}

inline void PushDown(int p) {
    if(rev[p]) {
        swap(ls(p), rs(p));
        if(ls(p))
            rev[ls(p)] ^= 1;
        if(rs(p))
            rev[rs(p)] ^= 1;
        rev[p] = 0;
    }
}

void SplitRank(int p, int rk, int &x, int &y) {
    if(!p) {
        x = y = 0;
        return;
    }
    PushDown(p);
    if(rk <= siz[ls(p)]) {
        y = p;
        SplitRank(ls(p), rk, x, ls(p));
        PushUp(y);
    } else {
        x = p;
        SplitRank(rs(p), rk - siz[ls(p)] - 1, rs(p), y);
        PushUp(x);
    }
}

int Merge(int x, int y) {
    if(!x || !y)
        return x | y;
    if(rnd[x] < rnd[y]) {
        PushDown(x);
        rs(x) = Merge(rs(x), y);
        PushUp(x);
        return x;
    } else {
        PushDown(y);
        ls(y) = Merge(x, ls(y));
        PushUp(y);
        return y;
    }
}

int NewNode(int v) {
    int p = ++tot;
    ch[p][0] = ch[p][1] = 0;
    val[p] = v, rnd[p] = rand();
    siz[p] = 1;
    rev[p]=false;
    return p;
}


//O(n)建树，返回新树的根
int st[MAXN], stop;
char buf[MAXN];
inline int Build(int n) {
    stop = 0;
    for(int i = 0; i < n; ++i) {
        int tmp = NewNode(buf[i]), last = 0;
        while(stop && rnd[st[stop]] > rnd[tmp]) {
            last = st[stop];
            PushUp(last);
            st[stop--] = 0;
        }
        if(stop)
            rs(st[stop]) = tmp;
        ls(tmp) = last;
        st[++stop] = tmp;
    }
    while(stop)
        PushUp(st[stop--]);
    return st[1];
}

inline void Move() {
    scanf("%d", &cur);
}

inline void Insert(int &root) {
    int x = 0, y = 0, z = 0, n;
    SplitRank(root, cur, x, z);
    scanf("%d", &n);
    getchar();
    buf[n] = '\0';
    for(int i = 0; i < n; ++i){
        buf[i] = getchar();
    }
    y = Build(n);
    root = Merge(Merge(x, y), z);
}

inline void Delete(int &root) {
    int x = 0, y = 0, z = 0, n;
    SplitRank(root, cur, x, y);
    scanf("%d", &n);
    SplitRank(y, n, y, z);
    //会不会太慢了
    //UnBuild(y);
    //y=Merge(ls(y),rs(y));
    root = Merge(x, z);
}

void Show(int p) {
    if(!p)
        return;
    PushDown(p);
    Show(ls(p));
    if(val[p]!='\n')
        putchar(val[p]);
    else
        printf("\\n");
    Show(rs(p));
}

inline void Get(int &root) {
    int x = 0, y = 0, z = 0, n = 0;
    SplitRank(root, cur, x, y);
    SplitRank(y, 1, y, z);
    putchar(val[y]);
    if(val[y]!='\n')
        putchar('\n');
    root = Merge(Merge(x, y), z);
}

inline void Prev() {
    --cur;
}

inline void Next() {
    ++cur;
}

void Reverse(int &root) {
    int l = cur+1, r;
    scanf("%d", &r);
    r = l + r - 1;
    //cout<<"l="<<l<<" r="<<r<<endl;
    int x = 0, y = 0, z = 0;
    SplitRank(root, l - 1, x, y);
    SplitRank(y, r + 1 - l, y, z);
    rev[y] ^= 1;
    root = Merge(Merge(x, y), z);
}

char op[20];
int main() {
#ifdef Yinku
    freopen("Yinku.in", "r", stdin);
#endif // Yinku
    int t;
    scanf("%d", &t);
    Init();
    while(t--) {
        scanf("%s", op);
        switch(op[0]) {
            case 'M':
                Move();
                break;
            case 'I':
                Insert(root);
                break;
            case 'D':
                Delete(root);
                break;
            case 'R':
                Reverse(root);
                break;
            case 'G':
                Get(root);
                break;
            case 'P':
                Prev();
                break;
            case 'N':
                Next();
                break;
        }
        /*printf("op=%s\n",op);
        int x=0,y=0;
        SplitRank(root,cur,x,y);
        Show(x);
        putchar('|');
        Show(y);
        putchar('\n');
        root=Merge(x,y);*/
    }
    return 0;
}