#ifndef _AVL_TREE_H
#define _AVL_TREE_H

struct AvlNode;
typedef struct AvlNode *Position;
typedef struct AvlNode *AvlTree;
typedef int elem_t;

AvlTree make_empty(AvlTree t);
Position find(elem_t x, AvlTree t);
Position find_min(AvlTree t);
Position find_max(AvlTree t);
AvlTree insert(elem_t x, AvlTree t);
AvlTree delete(elem_t x, AvlTree t);
elem_t retrieve(Position p);

/* for print node, place impl in header file */
struct AvlNode
{
    elem_t elem;
    AvlTree left;
    AvlTree right;
    int height;
};
typedef AvlTree Tree;

#endif