算法05

创建一颗二叉树使用递归版实现前中后序遍历这颗二叉树和使用队列实现层序遍历

#include<iostream>
#include<queue>
#include<cstdio>
using namespace std;


struct TreeNode
{
    char data;
    TreeNode *lchild, *rchild;
};


class Tree
{
private:
    TreeNode *head;
    queue<TreeNode *> q;
public:
    Tree()
    {
        head = NULL;
    }


public:
    void    create_tree()
    {
        cout << "请按照前序遍历的方式建造一棵树，#代表空节点!\n";
        _cree_tree(head);
    }
protected:
    void   _cree_tree(TreeNode * &t)
    {
        char ch;
        cin >> ch;
        if ('#' == ch)
        {
            t = NULL;
            return;
        }
        t = new TreeNode;
        t->data = ch;
        _cree_tree(t->lchild);
        _cree_tree(t->rchild);
    }
public:
    void prelook()
    {
        if (NULL == head)
        {
            cout << "这是一颗空树\n";
            return;
        }
        cout << "前序遍历:";
        _prelook(head);
        cout << endl;
    }
protected:
    void _prelook(TreeNode * &t)
    {
        if (NULL == t)
        {
            return;
        }
        cout << t->data << " ";
        _prelook(t->lchild);
        _prelook(t->rchild);
    }


public:
    void inlook()
    {
        if (NULL == head)
        {
            cout << "这是一颗空树\n";
            return;
        }
        cout << "中序遍历:";
        _inlook(head);
        cout << endl;
    }
protected:
    void _inlook(TreeNode * &t)
    {
        if (NULL == t)
        {
            return;
        }
        _inlook(t->lchild);
        cout << t->data << " ";
        _inlook(t->rchild);
    }


public:
    void endlook()
    {
        if (NULL == head)
        {
            cout << "这是一颗空树\n";
            return;
        }
        cout << "后序遍历:";
        _endlook(head);
        cout << endl;
    }
protected:
    void _endlook(TreeNode * &t)
    {
        if (NULL == t)
        {
            return;
        }
        _endlook(t->lchild);
        _endlook(t->rchild);
        cout << t->data << " ";
    }


public:
    void levellook()
    {
        if (NULL == head)
        {
            cout << "这是一颗空树!\n";
            return;
        }
        cout << "层序遍历:";
        _begin(head);
        _next();
        cout << endl;
    }
protected:
    void _begin(TreeNode* & t)
    {
        q.push(t);
    }
    void _next()
    {
        while (!q.empty())
        {
            TreeNode * item = q.front();
            q.pop();
            cout << item->data << " ";
            if (NULL != item->lchild)
            {
                q.push(item->lchild);
            }
            if (NULL != item->rchild)
            {
                q.push(item->rchild);
            }
        }
    }


public:
    ~Tree()
    {
        _delete(head);
    }
protected:
    void _delete(TreeNode * & t)
    {
        if (NULL == t)
        {
            return;
        }
        _delete(t->lchild);
        _delete(t->rchild);
        delete t;
    }
};


int main()
{
    while (true)
    {
        Tree tree;
        char ch;
        cout << "如果要创建一颗树请输入1，否则输入2:";
        cin >> ch;
        int flag = 1;
        switch (ch)
        {
        case '1':
            tree.create_tree();
            break;
        case '2':
            break;
        default:
            cout << "你的输入有问题,请重新输入\n";
            flag = 0;
            break;
        }
        if (0 == flag)
        {
            continue;
        }
        if ('2' == ch)
        {
            break;
        }
        while (true)
        {
            cout << "请选择你要进行的操作! 1.前序遍历 2.中序遍历 3.后续遍历 4.层序遍历 其他输入退出操作\n";
            char order;
            cin >> order;
            switch (order)
            {
            case '1':
                tree.prelook();
                break;
            case '2':
                tree.inlook();
                break;
            case '3':
                tree.endlook();
                break;
            case '4':
                tree.levellook();
                break;
            default:
                order = '#';
                break;
            }
            getchar();
            if ('#' == order)
            {
                break;
            }
        }
    }
    return 0;

}

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