【數據結構】64_二叉樹中的結點刪除與清除

二叉樹中的結點刪除

刪除方式

  • 基於數據元素值的刪除node

    • SharedPointer<Tree<T>> remove(const T &value);
  • 基於結點的刪除ios

    • SharedPointer<Tree<T>> remove(TreeNode<T> *node);

二叉樹中結點的刪除

image.png

刪除操做功能的定義

  • void removeP(BTreeNode<T> node, Btree<T> *&ret);編程

    • 將 node 做爲根結點的子樹從原來的二叉樹中刪除
    • ret 做爲子樹返回 (ret 指向堆空間中的二叉樹對象)

image.png

編程實驗:二叉樹結點的刪除操做

#ifndef BTREE_H
#define BTREE_H

#include "Tree.h"
#include "BTreeNode.h"
#include "Exception.h"
#include "LinkQueue.h"

namespace DTLib
{

template <typename T>
class BTree : public Tree<T>
{
public:
    BTree() = default;

    bool insert(TreeNode<T> *node) override
    {
        return insert(node, ANY);
    }

    virtual bool insert(TreeNode<T> *node, BTNodePos pos)
    {
        bool ret = true;

        if (node != nullptr)
        {
            if (this->m_root == nullptr)
            {
                node->parent = nullptr;
                this->m_root = node;
            }
            else
            {
                BTreeNode<T> *np = find(node->parent);

                if (np != nullptr)
                {
                    ret = insert(dynamic_cast<BTreeNode<T>*>(node), np, pos);
                }
                else
                {
                    THROW_EXCEPTION(InvalidParameterExcetion, "Invalid parent tree node ...");
                }
            }
        }
        else
        {
            THROW_EXCEPTION(InvalidParameterExcetion, "Parameter can not be null ...");
        }

        return ret;
    }

    bool insert(const T &value, TreeNode<T> *parent) override
    {
        return insert(value, parent, ANY);
    }

    virtual bool insert(const T &value, TreeNode<T> *parent, BTNodePos pos)
    {
        bool ret = true;
        BTreeNode<T> *node = BTreeNode<T>::NewNode();

        if (node != nullptr)
        {
            node->value = value;
            node->parent = parent;

            ret = insert(node, pos);

            if (!ret)
            {
                delete node;
            }
        }
        else
        {
            THROW_EXCEPTION(NoEnoughMemoryException, "No enough memory to create node ...");
        }

        return ret;
    }

    SharedPointer<Tree<T>> remove(const T &value) override
    {
        BTree<T> *ret = nullptr;

        BTreeNode<T> *node = find(value);

        if (node != nullptr)
        {
            remove(node, ret);
        }
        else
        {
            THROW_EXCEPTION(InvalidParameterExcetion, "Can not find the tree node via value ...");
        }

        return ret;
    }

    SharedPointer<Tree<T>> remove(TreeNode<T> *node) override
    {
        BTree<T> *ret = nullptr;

        node = find(node);

        if (node != nullptr)
        {
            remove(dynamic_cast<BTreeNode<T>*>(node), ret);
        }
        else
        {
            THROW_EXCEPTION(InvalidParameterExcetion, "Parameter node is invalid ...");
        }

        return ret;
    }

    BTreeNode<T>* find(const T &value) const override
    {
        return find(root(), value);
    }

    BTreeNode<T>* find(TreeNode<T> *node) const override
    {
        return find(root(), dynamic_cast<BTreeNode<T>*>(node));
    }

    BTreeNode<T>* root() const override
    {
        return dynamic_cast<BTreeNode<T>*>(this->m_root);
    }

    int degree() const override
    {
        return 0;
    }

    int count() const override
    {
        return 0;
    }

    int height() const
    {
        return 0;
    }

    void clear() override
    {
        this->m_root = nullptr;
    }

    ~BTree()
    {
        clear();
    }

protected:
    BTree(const BTree<T>&) = default;
    BTree<T>& operator = (const BTree<T>&) = default;

    virtual BTreeNode<T>* find(BTreeNode<T> *node, const T &value) const
    {
        BTreeNode<T> *ret = nullptr;

        if (node != nullptr)
        {
            if (node->value == value)
            {
                ret = node;
            }
            else
            {
                if (ret == nullptr)
                {
                    ret = find(node->left, value);
                }

                if (ret == nullptr)
                {
                    ret = find(node->right, value);
                }
            }
        }

        return ret;
    }

    virtual BTreeNode<T>* find(BTreeNode<T> *node, BTreeNode<T> *obj) const
    {
        BTreeNode<T> *ret = nullptr;

        if (node == obj)
        {
            ret = node;
        }
        else
        {
            if (node != nullptr)
            {
                if (ret == nullptr)
                {
                    ret = find(node->left, obj);
                }

                if (ret == nullptr)
                {
                    ret = find(node->right, obj);
                }
            }
        }

        return ret;
    }

    virtual bool insert(BTreeNode<T> *node, BTreeNode<T> *np, BTNodePos pos)
    {
        bool ret = true;

        if (pos == ANY)
        {
            if (np->left == nullptr)
            {
                np->left = node;
            }
            else if (np->right == nullptr)
            {
                np->right = node;
            }
            else
            {
                ret = false;
            }
        }
        else if (pos == LEFT)
        {
            if (np->left == nullptr)
            {
                np->left = node;
            }
            else
            {
                ret = false;
            }
        }
        else if (pos == RIGHT)
        {
            if (np->right == nullptr)
            {
                np->right = node;
            }
            else
            {
                ret = false;
            }
        }

        return ret;
    }

    virtual void remove(BTreeNode<T> *node, BTree<T> *&ret)
    {
        ret = new BTree<T>();

        if (ret != nullptr)
        {
            if (root() == node)
            {
                this->m_root = nullptr;
            }
            else
            {
                BTreeNode<T> *parent = dynamic_cast<BTreeNode<T>*>(node->parent);

                if (node == parent->left)
                {
                    parent->left = nullptr;
                }
                else if (node == parent->right)
                {
                    parent->right = nullptr;
                }

                node->parent = nullptr;
            }

            ret->m_root = node;
        }
        else
        {
            THROW_EXCEPTION(NoEnoughMemoryException, "No memory to create btree ...");
        }
    }
};

}

#endif // BTREE_H

文件:main.cppide

#include <iostream>
#include "BTreeNode.h"
#include "BTree.h"

using namespace std;
using namespace DTLib;

int main()
{
    BTree<int> bt;
    BTreeNode<int> *n = nullptr;

    bt.insert(1, nullptr);

    n = bt.find(1);
    bt.insert(2, n);
    bt.insert(3, n);

    n = bt.find(2);
    bt.insert(4, n);
    bt.insert(5, n);

    n = bt.find(4);
    bt.insert(8, n);
    bt.insert(9, n);

    n = bt.find(5);
    bt.insert(10, n);

    n = bt.find(3);
    bt.insert(6, n);
    bt.insert(7, n);

    SharedPointer<Tree<int>> sp = bt.remove(3);

    int a[] = {8, 9, 10, 6, 7};

    for (int i=0; i<5; ++i)
    {
        TreeNode<int> *node = bt.find(a[i]);

        while (node)
        {
            cout << node->value << " ";
            node = node->parent;
        }

        cout << endl;
    }

    cout << "----------" << endl;

    for (int i=0; i<5; ++i)
    {
        TreeNode<int> *node = sp->find(a[i]);

        while (node)
        {
            cout << node->value << " ";
            node = node->parent;
        }

        cout << endl;
    }

    return 0;
}

輸出:this

8 4 2 1
9 4 2 1
10 5 2 1


----------



6 3
7 3

二叉樹的清除

清除操做的定義

  • void clear();spa

    • 將二叉樹中的全部結點清除 (釋放堆中的結點)

二叉樹中結點的清除

image.png

清除操做的功能定義

  • free(node)code

    • 清除 node 爲根節點的二叉樹
    • 釋放二叉樹中的每個結點

image.png

編程實驗:清除二叉樹中的結點

文件:BTree.h對象

#ifndef BTREE_H
#define BTREE_H

#include "Tree.h"
#include "BTreeNode.h"
#include "Exception.h"
#include "LinkQueue.h"

namespace DTLib
{

template <typename T>
class BTree : public Tree<T>
{
public:
    BTree() = default;

    bool insert(TreeNode<T> *node) override
    {
        return insert(node, ANY);
    }

    virtual bool insert(TreeNode<T> *node, BTNodePos pos)
    {
        bool ret = true;

        if (node != nullptr)
        {
            if (this->m_root == nullptr)
            {
                node->parent = nullptr;
                this->m_root = node;
            }
            else
            {
                BTreeNode<T> *np = find(node->parent);

                if (np != nullptr)
                {
                    ret = insert(dynamic_cast<BTreeNode<T>*>(node), np, pos);
                }
                else
                {
                    THROW_EXCEPTION(InvalidParameterExcetion, "Invalid parent tree node ...");
                }
            }
        }
        else
        {
            THROW_EXCEPTION(InvalidParameterExcetion, "Parameter can not be null ...");
        }

        return ret;
    }

    bool insert(const T &value, TreeNode<T> *parent) override
    {
        return insert(value, parent, ANY);
    }

    virtual bool insert(const T &value, TreeNode<T> *parent, BTNodePos pos)
    {
        bool ret = true;
        BTreeNode<T> *node = BTreeNode<T>::NewNode();

        if (node != nullptr)
        {
            node->value = value;
            node->parent = parent;

            ret = insert(node, pos);

            if (!ret)
            {
                delete node;
            }
        }
        else
        {
            THROW_EXCEPTION(NoEnoughMemoryException, "No enough memory to create node ...");
        }

        return ret;
    }

    SharedPointer<Tree<T>> remove(const T &value) override
    {
        BTree<T> *ret = nullptr;

        BTreeNode<T> *node = find(value);

        if (node != nullptr)
        {
            remove(node, ret);
        }
        else
        {
            THROW_EXCEPTION(InvalidParameterExcetion, "Can not find the tree node via value ...");
        }

        return ret;
    }

    SharedPointer<Tree<T>> remove(TreeNode<T> *node) override
    {
        BTree<T> *ret = nullptr;

        node = find(node);

        if (node != nullptr)
        {
            remove(dynamic_cast<BTreeNode<T>*>(node), ret);
        }
        else
        {
            THROW_EXCEPTION(InvalidParameterExcetion, "Parameter node is invalid ...");
        }

        return ret;
    }

    BTreeNode<T>* find(const T &value) const override
    {
        return find(root(), value);
    }

    BTreeNode<T>* find(TreeNode<T> *node) const override
    {
        return find(root(), dynamic_cast<BTreeNode<T>*>(node));
    }

    BTreeNode<T>* root() const override
    {
        return dynamic_cast<BTreeNode<T>*>(this->m_root);
    }

    int degree() const override
    {
        return 0;
    }

    int count() const override
    {
        return 0;
    }

    int height() const
    {
        return 0;
    }

    void clear() override
    {
        free(root());

        this->m_root = nullptr;
    }

    ~BTree()
    {
        clear();
    }

protected:
    BTree(const BTree<T>&) = default;
    BTree<T>& operator = (const BTree<T>&) = default;

    virtual BTreeNode<T>* find(BTreeNode<T> *node, const T &value) const
    {
        BTreeNode<T> *ret = nullptr;

        if (node != nullptr)
        {
            if (node->value == value)
            {
                ret = node;
            }
            else
            {
                if (ret == nullptr)
                {
                    ret = find(node->left, value);
                }

                if (ret == nullptr)
                {
                    ret = find(node->right, value);
                }
            }
        }

        return ret;
    }

    virtual BTreeNode<T>* find(BTreeNode<T> *node, BTreeNode<T> *obj) const
    {
        BTreeNode<T> *ret = nullptr;

        if (node == obj)
        {
            ret = node;
        }
        else
        {
            if (node != nullptr)
            {
                if (ret == nullptr)
                {
                    ret = find(node->left, obj);
                }

                if (ret == nullptr)
                {
                    ret = find(node->right, obj);
                }
            }
        }

        return ret;
    }

    virtual bool insert(BTreeNode<T> *node, BTreeNode<T> *np, BTNodePos pos)
    {
        bool ret = true;

        if (pos == ANY)
        {
            if (np->left == nullptr)
            {
                np->left = node;
            }
            else if (np->right == nullptr)
            {
                np->right = node;
            }
            else
            {
                ret = false;
            }
        }
        else if (pos == LEFT)
        {
            if (np->left == nullptr)
            {
                np->left = node;
            }
            else
            {
                ret = false;
            }
        }
        else if (pos == RIGHT)
        {
            if (np->right == nullptr)
            {
                np->right = node;
            }
            else
            {
                ret = false;
            }
        }

        return ret;
    }

    virtual void remove(BTreeNode<T> *node, BTree<T> *&ret)
    {
        ret = new BTree<T>();

        if (ret != nullptr)
        {
            if (root() == node)
            {
                this->m_root = nullptr;
            }
            else
            {
                BTreeNode<T> *parent = dynamic_cast<BTreeNode<T>*>(node->parent);

                if (node == parent->left)
                {
                    parent->left = nullptr;
                }
                else if (node == parent->right)
                {
                    parent->right = nullptr;
                }

                node->parent = nullptr;
            }

            ret->m_root = node;
        }
        else
        {
            THROW_EXCEPTION(NoEnoughMemoryException, "No memory to create btree ...");
        }
    }

    virtual void free(BTreeNode<T> *node)
    {
        if (node != nullptr)
        {
            free(node->left);
            free(node->right);

            if (node->flag())
            {
                delete node;
            }
        }
    }
};

}

#endif // BTREE_H

文件:main.cppblog

#include <iostream>
#include "BTreeNode.h"
#include "BTree.h"

using namespace std;
using namespace DTLib;

int main()
{
    BTree<int> bt;
    BTreeNode<int> *n = nullptr;

    bt.insert(1, nullptr);

    n = bt.find(1);
    bt.insert(2, n);
    bt.insert(3, n);

    n = bt.find(2);
    bt.insert(4, n);
    bt.insert(5, n);

    n = bt.find(4);
    bt.insert(8, n);
    bt.insert(9, n);

    n = bt.find(5);
    bt.insert(10, n);

    n = bt.find(3);
    bt.insert(6, n);
    bt.insert(7, n);

    bt.clear();

    int a[] = {8, 9, 10, 6, 7};

    for (int i=0; i<5; ++i)
    {
        TreeNode<int> *node = bt.find(a[i]);

        while (node)
        {
            cout << node->value << " ";
            node = node->parent;
        }

        cout << endl;
    }

    return 0;
}

輸出:內存

小結

  • 刪除操做將目標結點所表明的子樹移除
  • 刪除操做必須完善處理父結點和子結點的關係
  • 清除操做用於銷燬樹中的每一個結點
  • 銷燬結點時判斷是否釋放對應的內存空間(工廠模式)

以上內容整理於狄泰軟件學院系列課程,請你們保護原創!

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