【数据结构】二叉树的创建、遍历以及广度深度优先搜索的实现

先序、中序、后序遍历主要依靠递归来实现

广度优先搜索主要依靠队列（先进先出），深度优先依靠栈（先进后出）

#include<iostream>
using namespace std;
template<class T>
struct Node {
    T data;
    Node<T> *next;
};
template<class T>
class LinkStack {
private:
    Node<T> *top;
public:
    LinkStack();
    ~LinkStack();
    void Push(T x);
    T Pop();
    T Top();
    bool Empty();
};
template<class T>
LinkStack<T>::LinkStack()
{
    top = NULL;
}
template<class T>
LinkStack<T>::~LinkStack()
{
    Node<T> *p = top;
    while (p)
    {
        Node<T> *q = p;
        p = p->next;
        delete q;
    }
    top = NULL;
}
template<class T>
void LinkStack<T>::Push(T x)
{
    Node<T> *s = new Node<T>();
    s->data = x;
    s->next = top;
    top = s;
}
template<class T>
T LinkStack<T>::Pop()
{
    T x;
    if (top == NULL)
    {
        cout << "下溢" << endl;
        exit(1);
    }
    x = top->data;
    Node<T> *p = top;
    top = top->next;
    delete p;
    return x;
}
template<class T>
T LinkStack<T>::Top()
{
    if (top == NULL)
    {
        cout << "下溢" << endl;
        exit(1);
    }
    return top->data;
}
template<class T>
bool LinkStack<T>::Empty()
{
    return top == NULL;
}
栈的模板定义，点击查看
#include<iostream>
using namespace std;
template<class T>
struct QNode {
    T data;
    QNode *next;
};
template<class T>
class LinkQueue {
private:
    QNode<T> *front, *rear;
public:
    LinkQueue();
    ~LinkQueue();
    void EnQueue(T x);
    T DeQueue();
    T GetQueue();
    bool Empty();
    void print();
};
template<class T>
LinkQueue<T>::~LinkQueue()
{
    rear = front = NULL;
}
template<class T>
void LinkQueue<T>::print()
{
    if (Empty())
    {
        cout << "队列为空！" << endl;

    }
    else
    {
        QNode<T> *p = front->next;
        while (p != NULL)
        {
            cout << p->data << " ";
            p = p->next;
        }
    }
    cout << endl;
}
template<class T>
LinkQueue<T>::LinkQueue()
{
    QNode<T> *s = new QNode<T>();
    s->next = NULL;
    front = rear = s;
}
template<class T>
T LinkQueue<T>::DeQueue()
{
    if (rear == front)
    {
        cout << "下溢" << endl;    //即队列为空
        exit(1);
    }
    QNode<T> *p = front->next;
    T x = p->data;
    front->next = p->next;
    if (p->next == NULL)
    {
        rear = front;
    }
    delete p;
    return x;
}
template<class T>
T LinkQueue<T>::GetQueue()
{
    if (rear == front)
    {
        cout << "下溢" << endl;    //即队列为空
        exit(1);
    }
    return front->next->data;
}
template<class T>
void LinkQueue<T>::EnQueue(T x)
{
    QNode<T> *s = new QNode<T>();
    s->data = x;
    s->next = NULL;
    rear->next = s;
    rear = s;
}
template<class T>
bool LinkQueue<T>::Empty()
{
    return rear == front;
}
队列的模板定义，点击查看

这两个其实主要是类的定义不同，但struct的定义是一样的，所以可以自己优化一下。

当然也可以直接调用c++标准库里的<stack> <queue> 都是可以直接使用的，在文章最后会放出标准代码，与上面的代码函数定义名称稍有不同。

#include<iostream>
#include<cstring>
#include"Stack.h"
#include"Queue.h"
using namespace std;
template<class T>
struct BTNode {
    T data;
    BTNode<T> *lchild, *rchild;
};
template<class T>
class BTree {
private:
    BTNode<T> *root;
    void pre_Order(BTNode<T> * t);
    void in_Order(BTNode<T> * t);
    void post_Order(BTNode<T> * t);
    void depthFirstSearch(BTNode<T> * t);
    void breadthFirstSearch(BTNode<T> *t);
    BTNode<T>* create(char s[],int &pos);
public:
    int length;
    void createBiTree();
    void preOrder();
    void inOrder();
    void postOrder();
    void DepthFirstSearch();
    void BreadthFirstSearch();
};
template<class T>
void BTree<T>::breadthFirstSearch(BTNode<T> *t)
{
    LinkQueue<BTNode<T>*> nodeQueue;
    nodeQueue.EnQueue(t);
    while (!nodeQueue.Empty())
    {
        BTNode<T> *node = nodeQueue.GetQueue();
        cout << node->data << ' ';
        nodeQueue.DeQueue();
        if (node->lchild)
        {
            nodeQueue.EnQueue(node->lchild);
        }
        if (node->rchild)
        {
            nodeQueue.EnQueue(node->rchild);
        }
    }
}
template<class T>
void BTree<T>::BreadthFirstSearch()
{
    cout << "广度优先搜索:";
    breadthFirstSearch(root);
    cout << endl;
}
template<class T>
void BTree<T>::depthFirstSearch(BTNode<T> *t)
{
    LinkStack <BTNode<T>*> nodeStack;
    nodeStack.Push(t);
    while (!nodeStack.Empty())
    {
        BTNode<T> *node = nodeStack.Top();
        cout << node->data << ' ';
        nodeStack.Pop();
        if (node->rchild)
        {
            nodeStack.Push(node->rchild);
        }
        if (node->lchild)
        {
            nodeStack.Push(node->lchild);
        }
    }
}
template<class T>
void BTree<T>::DepthFirstSearch()
{
    cout << "深度优先搜索:";
    depthFirstSearch(root);
    cout << endl;
}
template<class T>
BTNode<T>* BTree<T>::create(char s[], int &pos)
{
    ++pos;
    BTNode<T> *p;
    if (pos >= length)
    {
        return NULL;
    }
    else
    {
        if (s[pos] == '#')
        {
            p = NULL;
        }
        else
        {
            p = new BTNode<T>();
            p->data = s[pos];
            p->lchild = create(s,pos);
            p->rchild = create(s,pos);
        }
        return p;
    }
}
template<class T>
void BTree<T>::in_Order(BTNode<T> *t)
{
    if (t != NULL)
    {
        in_Order(t->lchild);
        cout << t->data << " ";
        in_Order(t->rchild);
    }
}
template<class T>
void BTree<T>::post_Order(BTNode<T> *t)
{
    if (t != NULL)
    {
        post_Order(t->lchild);
        post_Order(t->rchild);
        cout << t->data << " ";
    }
}
template<class T>
void BTree<T>::pre_Order(BTNode<T> *t)
{
    if (t != NULL)
    {
        cout << t->data << " ";
        pre_Order(t->lchild);
        pre_Order(t->rchild);
    }
}
template<class T>
void BTree<T>::createBiTree()
{
    cout << "请按照先序方式输入要创建的二叉树，#表示为空" << endl;
    int pos = -1;
    char str[50];
    cin >> str;
    length = strlen(str);
    root = create(str,pos);
    cout << "先序创建二叉树成功！" << endl;
}
template<class T>
void BTree<T>::preOrder()
{
    cout << "先序遍历:";
    pre_Order(root);
    cout << endl;
}
template<class T>
void BTree<T>::inOrder()
{
    cout << "中序遍历:";
    in_Order(root);
    cout << endl;
}
template<class T>
void BTree<T>::postOrder()
{
    cout << "后序序遍历:";
    post_Order(root);
    cout << endl;
}
int main()
{
    BTree<char> test;
    test.createBiTree();
    test.preOrder();
    test.inOrder();
    test.postOrder();
    test.DepthFirstSearch();
    test.BreadthFirstSearch();
    system("pause");
    return 0;
}
//ABD##EF##G##C#H##
#include<iostream>
#include<cstring>
#include<stack>
#include<queue>
using namespace std;
template<class T>
struct BTNode {
    T data;
    BTNode<T> *lchild, *rchild;
};
template<class T>
class BTree {
private:
    BTNode<T> *root;
    void pre_Order(BTNode<T> * t);
    void in_Order(BTNode<T> * t);
    void post_Order(BTNode<T> * t);
    void depthFirstSearch(BTNode<T> * t);
    void breadthFirstSearch(BTNode<T> *t);
    BTNode<T>* create(char s[],int &pos);
public:
    int length;
    void createBiTree();
    void preOrder();
    void inOrder();
    void postOrder();
    void DepthFirstSearch();
    void BreadthFirstSearch();
};
template<class T>
void BTree<T>::breadthFirstSearch(BTNode<T> *t)
{
    queue<BTNode<T>*> nodeQueue;
    nodeQueue.push(t);
    while (!nodeQueue.empty())
    {
        BTNode<T> *node = nodeQueue.front();
        cout << node->data << ' ';
        nodeQueue.pop();
        if (node->lchild)
        {
            nodeQueue.push(node->lchild);
        }
        if (node->rchild)
        {
            nodeQueue.push(node->rchild);
        }
    }
}
template<class T>
void BTree<T>::BreadthFirstSearch()
{
    cout << "广度优先搜索:";
    breadthFirstSearch(root);
    cout << endl;
}
template<class T>
void BTree<T>::depthFirstSearch(BTNode<T> *t)
{
    stack<BTNode<T>*> nodeStack;
    nodeStack.push(t);
    while (!nodeStack.empty())
    {
        BTNode<T> *node = nodeStack.top();
        cout << node->data << ' ';
        nodeStack.pop();
        if (node->rchild)
        {
            nodeStack.push(node->rchild);
        }
        if (node->lchild)
        {
            nodeStack.push(node->lchild);
        }
    }
}
template<class T>
void BTree<T>::DepthFirstSearch()
{
    cout << "深度优先搜索:";
    depthFirstSearch(root);
    cout << endl;
}
template<class T>
BTNode<T>* BTree<T>::create(char s[], int &pos)
{
    ++pos;
    BTNode<T> *p;
    if (pos >= length)
    {
        return NULL;
    }
    else
    {
        if (s[pos] == '#')
        {
            p = NULL;
        }
        else
        {
            p = new BTNode<T>();
            p->data = s[pos];
            p->lchild = create(s,pos);
            p->rchild = create(s,pos);
        }
        return p;
    }
}
template<class T>
void BTree<T>::in_Order(BTNode<T> *t)
{
    if (t != NULL)
    {
        in_Order(t->lchild);
        cout << t->data << " ";
        in_Order(t->rchild);
    }
}
template<class T>
void BTree<T>::post_Order(BTNode<T> *t)
{
    if (t != NULL)
    {
        post_Order(t->lchild);
        post_Order(t->rchild);
        cout << t->data << " ";
    }
}
template<class T>
void BTree<T>::pre_Order(BTNode<T> *t)
{
    if (t != NULL)
    {
        cout << t->data << " ";
        pre_Order(t->lchild);
        pre_Order(t->rchild);
    }
}
template<class T>
void BTree<T>::createBiTree()
{
    cout << "请按照先序方式输入要创建的二叉树，#表示为空" << endl;
    int pos = -1;
    char str[50];
    cin >> str;
    length = strlen(str);
    root = create(str,pos);
    cout << "先序创建二叉树成功！" << endl;
}
template<class T>
void BTree<T>::preOrder()
{
    cout << "先序遍历:";
    pre_Order(root);
    cout << endl;
}
template<class T>
void BTree<T>::inOrder()
{
    cout << "中序遍历:";
    in_Order(root);
    cout << endl;
}
template<class T>
void BTree<T>::postOrder()
{
    cout << "后序序遍历:";
    post_Order(root);
    cout << endl;
}
调用库的形式
int main()
{
    BTree<char> test;
    test.createBiTree();
    test.preOrder();
    test.inOrder();
    test.postOrder();
    test.DepthFirstSearch();
    test.BreadthFirstSearch();
    system("pause");
    return 0;
}
测试代码

测试输入：ABD##EF##G##C#H##

结果

请按照先序方式输入要创建的二叉树，#表示为空
ABD##EF##G##C#H##
先序创建二叉树成功！
先序遍历:A B D E F G C H
中序遍历:D B F E G A C H
后序序遍历:D F G E B H C A
深度优先搜索:A B D E F G C H
广度优先搜索:A B C D E H F G

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原文地址：https://www.cnblogs.com/robotpaul/p/9986265.html