数据结构---线索二叉树

#define QUEUE_MAXSIZE 50

typedef char DATA;

typedef enum
{
        SubTree,
        Thread

}NodeFlag;

//线索二叉树结构
typedef struct ThreadTree
{
        DATA data;
        NodeFlag lflag;
        NodeFlag rflag;
        struct ThreadTree *left;
        struct ThreadTree *right;
}ThreadBinTree;

ThreadBinTree *Previous = NULL;

//查找后继结点
ThreadBinTree *BinTreeNext_LDR(ThreadBinTree *bt)
{
        ThreadBinTree *nextnode;
        if(!bt) return NULL;
        if(bt->rflag == Thread)
                return bt->right;
        else
        {
                nextnode=bt->right;
                while(nextnode->lflag == SubTree)
                nextnode=nextnode->left;
                return nextnode;
        }

}

//查找前驱结点

ThreadBinTree *BinTreePrevious_LDR(ThreadBinTree *bt)
{
        ThreadBinTree *prenode;
        if(!bt) return NULL;
        if(bt->lflag == Thread)
                return bt->left;
        else
        {
                prenode = bt->left;
                while(prenode->rflag == SubTree)
                        prenode = prenode->left;
                return prenode;

        }

}

//遍历线索二叉树
void ThreadBinTree_LDR(ThreadBinTree *bt,void(*oper)(ThreadBinTree *p))
{
        if(bt)
        {
                while(bt->lflag == SubTree)
                bt=bt->left;
                do
                {
                        oper(bt);
                        bt=BinTreeNext_LDR(bt);
                }while(bt);
        }
}