Method erase

code/data-structures/avl_tree.cpp:74–74

    node *n = new node(item, prev);
    *cur = n, fix(n); return n; }
  void erase(const T &item) { erase(find(item)); }
  void erase(node *n, bool free = true) {
    if (!n) return;
    if (!n->l && n->r) parent_leg(n) = n->r, n->r->p = n->p;