txtgenbst.h

二叉树

//************************  genBST.h  **************************
//                 generic binary search tree

#include <queue>
#include <stack>

using namespace std;

#ifndef BINARY_SEARCH_TREE
#define BINARY_SEARCH_TREE

template<class T>
class Stack : public stack<T> {  //继承了模板stack类
public:
    T pop() {
        T tmp = top();
        stack<T>::pop();
        return tmp;
    }
};

template<class T>
class Queue : public queue<T> {  //继承了模板queue类
public:
    T dequeue() {
        T tmp = front();
        queue<T>::pop();
        return tmp;
    }
    void enqueue(const T& el) {
        push(el);
    }
};

template<class T>
class BSTNode {             // 一般搜索二叉树的节点定义
public:
    BSTNode() { 
        left = right = 0; 
    }
    BSTNode(const T& el, BSTNode *l = 0, BSTNode *r = 0) {
        key = el; left = l; right = r; 
    }
    T key;
    BSTNode *left, *right;
};

template<class T>
class BST {                  // 搜索二叉树的定义
public:
    BST() { 
        root = 0; 
    }
    ~BST() { 
        clear();
    }
    void clear() {
        clear(root); root = 0;
    }
    bool isEmpty() const { 
        return root == 0; 
    }
    void preorder() {     //前序遍历
        preorder(root);   
    }
    void inorder() {      //中序遍历
        inorder(root); 
    }
    void postorder() {    //后序遍历
        postorder(root);  
    }
    void insert(const T&);
    T* search(const T& el) const { 
        return search(root,el);
    }
    void deleteByCopying(BSTNode<T>*&);
    void findAndDeleteByCopying(const T&);
    void deleteByMerging(BSTNode<T>*&);
    void findAndDeleteByMerging(const T&);
    void iterativePreorder();
    void iterativeInorder();
    void iterativePostorder();
    void breadthFirst();
    void MorrisPreorder();
    void MorrisInorder();
    void MorrisPostorder();
    void balance(T*,int,int);
protected:
    BSTNode<T>* root;
    void clear(BSTNode<T>*);
    T* search(BSTNode<T>*, const T&) const;
    void preorder(BSTNode<T>*);
    void inorder(BSTNode<T>*);
    void postorder(BSTNode<T>*);
    virtual void visit(BSTNode<T>* p) { 
        cout << p->key << ' '; 
    }
};

template<class T>
void BST<T>::clear(BSTNode<T> *p) {
    if (p != 0) {
         clear(p->left);
         clear(p->right);
         delete p;
     }
}

template<class T>
void BST<T>::insert(const T& el) {   
    BSTNode<T> *p = root, *prev = 0;
    while (p != 0) {        // find a place for inserting new node;
        prev = p;
        if (p->key < el)
             p = p->right;
        else p = p->left;
    }
    if (root == 0)    // tree is empty;
         root = new BSTNode<T>(el);
    else if (prev->key < el)
         prev->right = new BSTNode<T>(el);
    else prev->left  = new BSTNode<T>(el);
}

template<class T>
T* BST<T>::search(BSTNode<T>* p, const T& el) const {
    while (p != 0)
        if (el == p->key)
             return &p->key;
        else if (el < p->key)
             p = p->left;
        else p = p->right;
    return 0;
}

template<class T>
void BST<T>::inorder(BSTNode<T> *p) {
     if (p != 0) {
         inorder(p->left);
         visit(p);
         inorder(p->right);
     }
}

template<class T>
void BST<T>::preorder(BSTNode<T> *p) {
    if (p != 0) {
        visit(p);
        preorder(p->left);
        preorder(p->right);
    }
}

template<class T>
void BST<T>::postorder(BSTNode<T>* p) {
    if (p != 0) {
        postorder(p->left);
        postorder(p->right);
        visit(p);
    }
}

template<class T>
void BST<T>::deleteByCopying(BSTNode<T>*& node) {    
    BSTNode<T> *previous, *tmp = node;
     if (node->right == 0)                  // node has no right child;
          node = node->left;   
     else if (node->left == 0)              // node has no left child;
          node = node->right;
     else {
          tmp = node->left;                 // node has both children;
          previous = node;                  // 1.
          while (tmp->right != 0) {         // 2.
              previous = tmp;
              tmp = tmp->right;
          }
          node->key = tmp->key;             // 3.
          if (previous == node)
               previous->left  = tmp->left;
          else previous->right = tmp->left; // 4.
     }
     delete tmp;                            // 5.
}

// findAndDeleteByCopying() searches the tree to locate the node containing
// el. If the node is located, the function DeleteByCopying() is called.

template<class T>
void BST<T>::findAndDeleteByCopying(const T& el) {    
    BSTNode<T> *p = root, *prev = 0;
     while (p != 0 && !(p->key == el)) {
         prev = p;
         if (p->key < el)
              p = p->right;
         else p = p->left;
     }
     if (p != 0 && p->key == el)
          if (p == root)
               deleteByCopying(root);
          else if (prev->left == p)
               deleteByCopying(prev->left);
          else deleteByCopying(prev->right);
     else if (root != 0)
          cout << "key " << el << " is not in the tree\n";
     else cout << "the tree is empty\n";
}

template<class T>
void BST<T>::deleteByMerging(BSTNode<T>*& node) {   
    BSTNode<T> *tmp = node;
    if (node != 0) {
        if (!node->right)           // node has no right child: its left
             node = node->left;     // child (if any) is attached to its parent;
        else if (node->left == 0)   // node has no left child: its right
             node = node->right;    // child is attached to its parent;
        else {                      // be ready for merging subtrees;
             tmp = node->left;      // 1. move left
             while (tmp->right != 0)// 2. and then right as far as possible;
                tmp = tmp->right;
             tmp->right =           // 3. establish the link between the
                node->right;        //    the rightmost node of the left
                                    //    subtree and the right subtree;
             tmp = node;            // 4.
             node = node->left;     // 5.
        }
        delete tmp;                 // 6.
     }
}

template<class T>
void BST<T>::findAndDeleteByMerging(const T& el) {    
    BSTNode<T> *node = root, *prev = 0;
    while (node != 0) {                 //寻找
        if (node->key == el)
             break;
        prev = node;
        if (node->key < el)
             node = node->right;
        else node = node->left;
    }
    if (node != 0 && node->key == el)
         if (node == root)
              deleteByMerging(root);
         else if (prev->left == node)
              deleteByMerging(prev->left);
         else deleteByMerging(prev->right);
    else if (root != 0)
         cout << "key " << el << " is not in the tree\n";
    else cout << "the tree is empty\n";
}

template<class T>
void BST<T>::iterativePreorder() {    
    Stack<BSTNode<T>*> travStack;
    BSTNode<T> *p = root;
    if (p != 0) {
        travStack.push(p);
        while (!travStack.empty()) {
            p = travStack.pop();
            visit(p);
            if (p->right != 0)
                 travStack.push(p->right);
            if (p->left != 0)             // left child pushed after right
                 travStack.push(p->left); // to be on the top of the stack;
        }
    }
}

template<class T>
void BST<T>::iterativeInorder() {    
    Stack<BSTNode<T>*> travStack;
    BSTNode<T> *p = root;
    while (p != 0) {
        while (p != 0) {                 // stack the right child (if any)
            if (p->right)                // and the node itself when going
               travStack.push(p->right); // to the left;
            travStack.push(p);
            p = p->left;
        }
        p = travStack.pop();             // pop a node with no left child
        while (!travStack.empty() && p->right == 0) { // visit it and all nodes
            visit(p);                                 // with no right child;
            p = travStack.pop();
        }
        visit(p);                        // visit also the first node with
        if (!travStack.empty())          // a right child (if any);
             p = travStack.pop();
        else p = 0;
    }
}

template<class T>
void BST<T>::iterativePostorder() {    
    Stack<BSTNode<T>*> travStack;
    BSTNode<T>* p = root, *q = root;
    while (p != 0) {
        for ( ; p->left != 0; p = p->left)
            travStack.push(p);
        while (p != 0 && (p->right == 0 || p->right == q)) {
            visit(p);
            q = p;
            if (travStack.empty())
                 return;
            p = travStack.pop();
        }
        travStack.push(p);
        p = p->right;
     }
}

template<class T>
void BST<T>::breadthFirst() {    //广度优先
    Queue<BSTNode<T>*> queue;
    BSTNode<T> *p = root;
    if (p != 0) {
        queue.enqueue(p);
        while (!queue.empty()) {
            p = queue.dequeue();
            visit(p);
            if (p->left != 0)
                 queue.enqueue(p->left);
            if (p->right != 0)
                 queue.enqueue(p->right);
        }
    }
}

template<class T>
void BST<T>::MorrisInorder() {   
    BSTNode<T> *p = root, *tmp;
    while (p != 0)
        if (p->left == 0) {
             visit(p);
             p = p->right;
        }
        else {
             tmp = p->left;
             while (tmp->right != 0 &&// go to the rightmost node of
                    tmp->right != p)  // the left subtree or
                  tmp = tmp->right;   // to the temporary parent of p;
             if (tmp->right == 0) {   // if 'true' rightmost node was
                  tmp->right = p;     // reached, make it a temporary
                  p = p->left;        // parent of the current root,
             }
             else {                   // else a temporary parent has been
                  visit(p);           // found; visit node p and then        cut
                  tmp->right = 0;     // the right pointer of the current
                  p = p->right;       // parent, whereby it ceases to be
             }                        // a parent;
        }
}

template<class T>
void BST<T>::MorrisPreorder() {
    BSTNode<T> *p = root, *tmp;
    while (p != 0) {
        if (p->left == 0) {
             visit(p);
             p = p->right;
        }
        else {
             tmp = p->left;
             while (tmp->right != 0 &&// go to the rightmost node of
                    tmp->right != p)  // the left subtree or
                  tmp = tmp->right;   // to the temporary parent of p;
             if (tmp->right == 0) {   // if 'true' rightmost node was
                  visit(p);           // reached, visit the root and
                  tmp->right = p;     // make the rightmost node a temporary
                  p = p->left;        // parent of the current root,
             }
             else {                   // else a temporary parent has been
                  tmp->right = 0;     // found; cut the right pointer of
                  p = p->right;       // the current parent, whereby it ceases
             }                        // to be a parent;
        }
    }
}

template<class T>
void BST<T>::MorrisPostorder() {
    BSTNode<T> *p = new BSTNode<T>(), *tmp, *q, *r, *s;
    p->left = root;
    while (p != 0)
        if (p->left == 0)
             p = p->right;
        else {
             tmp = p->left;
             while (tmp->right != 0 &&// go to the rightmost node of
                    tmp->right != p)  // the left subtree or
                  tmp = tmp->right;   // to the temporary parent of p;
             if (tmp->right == 0) {   // if 'true' rightmost node was
                  tmp->right = p;     // reached, make it a temporary
                  p = p->left;        // parent of the current root,
             }
             else {             // else a temporary parent has been found;
                  // process nodes between p->left (included) and p (excluded)
                  // extended to the right in modified tree in reverse order;
                  // the first loop descends this chain of nodes and reverses
                  // right pointers; the second loop goes back, visits nodes,
                  // and reverses right pointers again to restore the pointers
                  // to their original setting;
                  for (q = p->left, r = q->right, s = r->right;
                       r != p; q = r, r = s, s = s->right)
                      r->right = q;
                  for (s = q->right; q != p->left;
                      q->right = r, r = q, q = s, s = s->right)
                     visit(q);
                  visit(p->left);     // visit node p->left and then cut
                  tmp->right = 0;     // the right pointer of the current
                  p = p->right;       // parent, whereby it ceases to be
             }                        // a parent;
        }
}

template<class T>
void BST<T>::balance (T data[], int first, int last) {
    if (first <= last) {
        int middle = (first + last)/2;
        insert(data[middle]);
        balance(data,first,middle-1);
        balance(data,middle+1,last);
    }
}

#endif