二叉树的构造与遍历

二叉树是指一个树结点最多只有两个子结点的数据结构，分别称为左子结点，右子结点。抽象来看每个结点拥有左子树、右子树。本文所记录的二叉树的构造与遍历均为递归定义。

---

1.定义结点类

struct TreeNode{    int data;    TreeNode *lchild, *rchild;    TreeNode(int x = '#')        :data(x) {}};

---

2.定义二叉树类

class BinTree{public:    BinTree();    ~BinTree();    void creatTree(TreeNode *&root);    void clearTree(TreeNode *&root);    bool TreeEmpty();    int TreeDepth(TreeNode *root);    TreeNode *rootNode();    int nodeValue(TreeNode *node);    void assignNode(TreeNode *node,int val);    TreeNode *parentNode(TreeNode *root, TreeNode *node);    TreeNode *lchildNode(TreeNode *node);    TreeNode *rchildNode(TreeNode *node);    void preTraverse(TreeNode *root);    void midTraverse(TreeNode *root);    void postTraverse(TreeNode *root);    void setFactors(std::vector<int> nums);    void showFactors();    int getIndex();private:    TreeNode *root;    std::vector<int> factors;    int index;};

---

3.方法实现

#include "BiTreeLink.h"BinTree::BinTree(){    // this->root = new TreeNode     this->root = nullptr;    this->index = 0;}BinTree::~BinTree(){    clearTree(this->root);}void BinTree::creatTree(TreeNode *&root){    /*if (this->index >= this->factors.size())    {        return;    }*/    auto p = (this->index)++;    if (this->factors.at(p) == '#')    {        // return;        // TreeNode *root = new TreeNode();        root = nullptr;        //root = new TreeNode();    }    else    {        root = new TreeNode(factors.at(p));        creatTree(root->lchild);        creatTree(root->rchild);    }}void BinTree::clearTree(TreeNode *&root){    if (root)    {        if (root->lchild)        {            clearTree(root->lchild);        }        if (root->rchild)        {            clearTree(root->rchild);        }        delete root;        root = nullptr;    }}bool BinTree::TreeEmpty(){    return this->root == nullptr;}int BinTree::TreeDepth(TreeNode *root){    int i, j;    if (!root)    {        return 0;    }    if (root->lchild)    {        i = TreeDepth(root->lchild);    }    else    {        i = 0;    }    if (root->rchild)    {        j = TreeDepth(root->rchild);    }    else    {        j = 0;    }    return i > j ? i + 1 : j + 1;}TreeNode * BinTree::rootNode(){    return this->root;}int BinTree::nodeValue(TreeNode *node){    if (!TreeEmpty())    {        std::cout << node->data << std::endl;    }    return node->data;}void BinTree::assignNode(TreeNode *node,int val){    if (val != 0xFFFF && node)    {        node->data = val;    }}TreeNode * BinTree::parentNode(TreeNode *root, TreeNode *node){    if (root && node)    {        if (root->lchild == node || root->rchild == node)        {            return root;        }        else        {            parentNode(root->lchild, node);            parentNode(root->rchild, node);        }    }}TreeNode * BinTree::lchildNode(TreeNode *node){    return node->lchild;}TreeNode * BinTree::rchildNode(TreeNode *node){    return node->rchild;}void BinTree::preTraverse(TreeNode *root){    if (!root)    {        return;    }    std::cout << root->data << std::endl;    preTraverse(root->lchild);    preTraverse(root->rchild);}void BinTree::midTraverse(TreeNode *root){    if (!root)    {        return;    }    midTraverse(root->lchild);    std::cout << root->data << std::endl;    midTraverse(root->rchild);}void BinTree::postTraverse(TreeNode *root){    if (!root)    {        return;    }    postTraverse(root->lchild);    postTraverse(root->rchild);    std::cout << root->data << std::endl;}void BinTree::setFactors(std::vector<int> nums){    for (auto &n : nums)    {        this->factors.push_back(n);    }}void BinTree::showFactors(){    for (auto &f : this->factors)    {        std::cout << f << "=>";    }    std::cout << "END" << std::endl;}int BinTree::getIndex(){    return this->index;}