class PAIR { // A key-pointer pair stored in B+-tree nodes
public:
  void* ptr; // Elem* for leaves, BPNode* for internals
  int pkey;
};


class BPNode { // The B+-tree node class
public:
  PAIR recs[MAXREC];    // Array of key/pointer pairs
  int numrec;
  BPNode* lftptr;  BPNode* rghtptr; // Link the levels
  bool isLeaf() const;  // True if the node is a leaf
  bool isFull() const;  // True if the node is full
};