5)二叉树[2]二叉树中序线索化

#include "iostream"
#include "stdlib.h"
using namespace std;

typedef char type;
struct bnode{
    type data;
    bnode *lchild,*rchild;
    int rtag,ltag;
};

const int lrtag = 0;
class thbtree{
public:
    thbtree();//初始化
    ~thbtree();
    void create_thbtree(bnode *&T);//建立二叉树
    void inorder(bnode *T);//先序遍历
    bnode *in_thread(bnode *&T);
    void inthread(bnode *p,bnode *&pre);

private:
    int count;//元素个数统计
};

thbtree::thbtree()//初始化
{
    count = 0;
}

void thbtree::create_thbtree(bnode *&T)//建立二叉树
{
    type ch;
    cin>>ch;
    if(ch=='.')T=NULL;
    else {
        T = new bnode;
        T->data = ch;
        T->ltag = lrtag;
        T->rtag = lrtag;
        count++;
        create_thbtree(T->lchild);
        create_thbtree(T->rchild);
    }
}

void thbtree::inthread(bnode *p,bnode *&pre)
{
    if(p)
    {
        inthread(p->lchild,pre);//左子树线索化
        if(!p->lchild)//如果p的左子树为空，给P点加前驱线索
        {
            p->ltag = 1;
            p->lchild = pre;
        }else{
            p->ltag = 0;
        }
        if(pre && !pre->rchild)
        {
            pre->rtag = 1;
            pre->rchild = p;
        }
        pre = p;
        inthread(p->rchild,pre);//右子树线索化
    }
}
bnode *thbtree::in_thread(bnode *&T)
{
    bnode *pre = NULL;
    bnode *head;
    head =  new bnode;
    head->ltag = 0;
    head->rtag = 1;
    head->lchild = head;
    if(!T)
    {
        head->lchild = head;
    }else{
        head->lchild = T;
        pre = head;
        inthread(T,pre);
        pre->rchild = head;
        pre->rtag=1;
        head->rchild = pre;
    }
    T =head;
    return head;
}


void thbtree::inorder(bnode*T)//中序遍历
{
    bnode *p;
    p = T->lchild;
    while(p!=T)
    {
        while(p->ltag==0)
        {
            p=p->lchild;
        }
        cout<<p->data<<" ";
        while(p->rtag==1&&p->rchild!=T)
        {
            p = p->rchild;
            cout<<p->data<<" ";
        }
        p = p->rchild;
    }
}

thbtree::~thbtree(){}

int main()
{
    thbtree Tree;
    bnode *T;
    cout<<"Create Tree:";
    Tree.create_thbtree(T);
    cout<<"Tree finished!"<<endl;
    Tree.in_thread(T);
    cout<<"INorder Tree:";
    Tree.inorder(T);
    cout<<endl;
    return 0;
}