A binary search tree is implemented using the following node and class structure. Write a method void rank(int k, Entry &x) that returns the k-th ranked entry in x (assume 1<=k<=n where n is the number of items in the binary search tree.) Your method should stop the search as soon as the k-th item is found.

template <class Entry>

struct Binary_node {

// data members:

Entry data;

Binary_node *left;

Binary_node *right;

// constructors:

Binary_node( );

Binary_node(const Entry &x);

};

template <class Entry>

class Binary_tree {

public:

Binary_tree( );

bool rank(int k, Entry &x); // returns the k-th ranked entry in x

protected:

// Add auxiliary function prototypes here.

Binary_node *root;

};