模板汇总——splay

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

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

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

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

 int build(int ll, int rr){
     int p = , x;
     for(int i = rr; i >= ll; i--){
         x = ++tot;
         tr[x].init();
         tr[x].son[] = 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^];
     tr[tr[y].son[k]].pre = y;
     tr[x].son[k^] = 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 + ) return x;
     if(num <= tr[lch(x)].sz) return Find(num, lch(x));
     return Find(num - tr[lch(x)].sz - , rch(x));
 }
 void Insert_point(LL v, LL z){
     int p  = root, ff = ;
     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, );
 }

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