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#include <iostream>
using namespace std;
// Code Fragment: LinkedBinaryTree1
template <typename Object>
class LinkedBinaryTree {
protected:
// ... (insert Node definition here)
//Code Fragment: Node
struct Node { // a node in the tree
Object element; // the element
Node* parent; // parent
Node* left; // left child
Node* right; // right child
Node() : element(Object()) // default constructor
{ parent = left = right = NULL; }
Node* sibling() const { // get our sibling
return (this == parent->left ? parent->right : parent->left);
}
};
typedef Node* NodePtr; // a node pointer
public:
// ... (insert Position definition here)
//Code Fragment: Position
class Position { // position in the tree
private:
NodePtr node; // pointer to the node
public:
Position(NodePtr n = NULL) // constructor
{ node = n; }
Object& element() const // get element
{ return node->element; }
bool isNull() const // null position?
{ return node == NULL; }
friend class LinkedBinaryTree; // allow access
};
private: // member data
NodePtr theRoot; // pointer to the root
int sz; // number of nodes
protected: // protected utilities
// ... (insert LinkedBinaryTree utilities here)
//Code Fragment: LinkedBinaryTree2
// ... (utilities for LinkedBinaryTree)
NodePtr nodePtr(const Position& v) const // convert to NodePtr
{ return v.node; }
bool isExternal(NodePtr n) const // is node external?
{ return (n->left == NULL && n->right == NULL); }
bool isInternal(NodePtr n) const // is node internal?
{ return ! isExternal(n); }
bool isRoot(NodePtr n) const // is node the root?
{ return (n == theRoot); }
void setRoot(NodePtr r) // make r the root
{ theRoot = r; r->parent = NULL; }
void replaceElement(NodePtr n, const Object& o) // replace element
{ n->element = o; }
void swapElements(NodePtr n, NodePtr w) { // swap elements
Object temp = w->element;
w->element = n->element;
n->element = temp;
}
void expandExternal(NodePtr n) { // expand external node
n->left = new Node; n->left->parent = n;
n->right = new Node; n->right->parent = n;
sz += 2;
}
NodePtr removeAboveExternal(NodePtr n) { // remove n and parent
NodePtr p = n->parent;
NodePtr s = n->sibling();
if (isRoot(p)) setRoot(s); // p was root; now s is
else {
NodePtr g = p->parent; // the grandparent
if (p == g->left) g->left = s; // replace parent by sibling
else g->right = s;
s->parent = g;
}
delete n; delete p; // delete removed nodes
sz -= 2; // two fewer nodes
return s;
}
public:
LinkedBinaryTree() // constructor
{ theRoot = new Node; sz = 1; }
int size() const // size of tree
{ return sz; }
bool isEmpty() const // is tree empty?
{ return (sz == 0); }
Position root() const // returns root
{ return Position(theRoot); }
Position leftChild(const Position& v) const // returns left child
{ return Position(nodePtr(v)->left); }
Position rightChild(const Position& v) const // returns right child
{ return Position(nodePtr(v)->right); }
// ... parent(), and sibling() are omitted but similar)
bool isRoot(const Position& v) const // is v the root?
{ return isRoot(nodePtr(v)); }
bool isInternal(const Position& v) const // is v internal?
{ return isInternal(nodePtr(v)); }
bool isExternal(const Position& v) const // is v external?
{ return isExternal(nodePtr(v)); }
void replaceElement(const Position& v, const Object& o)
{ replaceElement(nodePtr(v), o); } // replace element
void swapElements(const Position& v, const Position& w)
{ swapElements(nodePtr(v), nodePtr(w)); } // swap elements
void expandExternal(const Position& v)
{ expandExternal(nodePtr(v)); } // expand external node
Position removeAboveExternal(const Position& v) // remove v and parent
{ return Position(removeAboveExternal(nodePtr(v))); }
// ... (housekeeping and iterator functions omitted)
};
class Int {
public:
Int() { counter++; num = counter; }
private:
static int counter;
int num;
friend ostream& operator<<(ostream& out, Int i);
};
ostream& operator<<(ostream& out, Int i)
{ out << i.num << " ";
return out;
}
typedef LinkedBinaryTree<Int> Tree;
typedef Tree::Position Position;
void binaryInorderPrint(const Tree& T, const Position& v)
{ if (T.isInternal(v)) // visit left child
binaryInorderPrint(T, T.leftChild(v));
cout << v.element(); // print element
if (T.isInternal(v)) // visit right child
binaryInorderPrint(T, T.rightChild(v));
}
int Int::counter = 0;
int main()
{ LinkedBinaryTree<Int> btree;
btree.expandExternal(btree.root());
binaryInorderPrint(btree, btree.root());
cout << endl;
btree.expandExternal(btree.leftChild(btree.root()));
binaryInorderPrint(btree, btree.root());
return 0;
}
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