const int MAX_NODES = 100; // maximum number of nodes
typedef string treeItemType;

struct treeNode            // node in the tree
{  treeItemType Item;      // data portion
   int          LChild;    // index to left child
   int          RChild;    // index to right child
};  // end struct

typedef treeNode arrayType[MAX_NODES];

arrayType Tree;  // array of tree nodes
int       Root;  // index of root
int       Free;  // index of free list