模板汇总——splay

#define lch(x) tr[x].son[0]
#define rch(x) tr[x].son[1]
const int N = 1e5 + 100;
int tot = 0, root;
struct Node{
    int son[2], pre, sz;
    void init(){ 
        sz = 1;
        son[0] = son[1] = pre = 0;
    }
}tr[N];

void Push_Rev(int x){
    if(!x) return ;
    swap(lch(x), rch(x));
    tr[x].rev ^= 1;
}
void Push_up(int x){
    if(!x) return;
    tr[x].sz = tr[lch(x)].sz + tr[rch(x)].sz + 1;
}

void Push_Down(int x){
   if(tr[x].rev){
        tr[x].rev = 0;
        Push_Rev(lch(x));
        Push_Rev(rch(x));
    }
}

void Reverse(int l, int r){
    int pl = Find(l, root);
    int pr = Find(r+2, root);
    Splay(pl, 0);
    Splay(pr, pl);
    Push_Rev(tr[pr].son[0]);
    Push_Up(tr[pr].son[0]);
    Push_Up(pr);
    Push_Up(pl);
}

int build(int ll, int rr){
    int p = 0, x;
    for(int i = rr; i >= ll; i--){
        x = ++tot;
        tr[x].init();
        tr[x].son[1] = p;
        tr[p].pre = x;
        Push_Up(x);
        p = x;
    }
    return x;
}

void rotate(int x){
    int y = tr[x].pre;
    int z = tr[y].pre;
    int k = x == rch(y);
    tr[x].pre = z;
    tr[z].son[y == rch(z)] = x;
    tr[y].son[k] = tr[x].son[k^1];
    tr[tr[y].son[k]].pre = y;
    tr[x].son[k^1] = y;
    tr[y].pre = x;
    Push_up(y);
}

void splay(int x, int goal){
    while(tr[x].pre != goal){
        int y = tr[x].pre;
        int z = tr[y].pre;
        if(z != goal){
            if((lch(y) == x) ^ (lch(z) == y))   rotate(x); ///x和y分别是y和z的同一段的儿子
            else rotate(y);
        }
        rotate(x);
    }
    if(!goal) root = x;
    Push_up(x);
}
int Find(int num, int x){
    Push_Down(x);
    if(num == tr[lch(x)].sz + 1) return x;
    if(num <= tr[lch(x)].sz) return Find(num, lch(x));
    return Find(num - tr[lch(x)].sz - 1, rch(x));
}
void Insert_point(LL v, LL z){
    int p  = root, ff = 0;
    while(p && tr[p].val != v){
        ff = p;
        p = tr[p].son[ tr[p].val < v];
    }
    if(p){
       tr[p].szz += z;
    }
    else {
        p = ++tot;
        if(ff) tr[ff].son[ tr[ff].val < v] = p;
        tr[p].init(v, z);
        tr[p].pre = ff;
    }
    splay(p, 0);
}

void Collect(int x){
    if(tr[x].son[0]) Clear(tr[x].son[0]);
    if(tr[x].son[1]) Clear(tr[x].son[1]);
    sta[++top] = x;
}
void Delete_tree(int l, int r){
    int pl = Find(l, root);
    int pr = Find(r+2, root);
    Splay(pl, 0);
    Splay(pr, pl);
    Collect(tr[pr].son[0]);
    tr[pr].son[0] = 0;
    Push_Up(pr);
    Push_Up(pl);
}

void dfs(int x){
    Push_down(x);
    if(lch(x)) dfs(lch(x));
    printf("%d ", tr[x].val);
    if(rch(x)) dfs(rch(x));
}