数据结构——中序线索二叉树及其中序遍历

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author's email:[email protected]
date:2017.12.25
中序遍历中序线索二叉树
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#include
using namespace std;
typedef struct TBTNode
{
	char data;
	int ltag, rtag;//线索标记
	struct TBTNode *lchild;
	struct TBTNode *rchild;
}TBTNode,*TBTree;
TBTree createTree();//创建一颗二叉树
void InThread(TBTNode *p, TBTNode *&pre);//通过中序遍历对二叉树线索化
void createInThread(TBTNode *root);//通过中序遍历建立中序线索二叉树
TBTNode *Frist(TBTNode *p);//中序序列下的第一个结点
TBTNode *Next(TBTNode *p);//结点p在中序下的后继结点
void Inorder(TBTNode *root);//对中序线索二叉树执行中序遍历
int main() 
{

	TBTree tbtree=createTree();
	createInThread(tbtree);

	cout << "中序线索二叉树的中序遍历：";
	Inorder(tbtree);
	cout << endl;

	return 0;
}
TBTree createTree() 
{
	TBTree pA = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pB = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pC = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pD = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pE = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pF = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pG = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pH = (TBTNode *)malloc(sizeof(TBTNode));
	TBTree pI = (TBTNode *)malloc(sizeof(TBTNode));


	pA->data = 'A';
	pB->data = 'B';
	pC->data = 'C';
	pD->data = 'D';
	pE->data = 'E';
	pF->data = 'F';
	pG->data = 'G';
	pH->data = 'H';
	pI->data = 'I';

	pA->lchild = pC;
	pA->rchild = pB;
	pC->lchild = pD;
	pC->rchild = pE;
	pB->rchild = pF;
	pB->lchild = NULL;
	pD->lchild = pG;
	pD->rchild = NULL;
	pE->lchild = NULL;
	pE->rchild = pH;
	pF->lchild = pI;
	pF->rchild = NULL;
	pG->lchild = pG->rchild = NULL;
	pH->lchild = pH->rchild = NULL;
	pI->lchild = pI->rchild = NULL;


	pA->ltag = pA->rtag = 0;
	pB->ltag = pB->rtag = 0;
	pC->ltag = pC->rtag = 0;
	pD->ltag = pD->rtag = 0;
	pE->ltag = pE->rtag = 0;
	pF->ltag = pF->rtag = 0;
	pG->ltag = pG->rtag = 0;
	pH->ltag = pH->rtag = 0;
	pI->ltag = pI->rtag = 0;	


	return pA;

}
//通过中序遍历对二叉树线索化
void InThread(TBTNode *p, TBTNode *&pre) 
{
	if (p != NULL) 
	{
		InThread(p->lchild, pre);//递归，左子树线索化
		if (p->lchild == NULL)//建立当前结点的前驱线索
		{
			p->lchild = pre;
			p->ltag = 1;
		}
		if (pre!= NULL&&pre->rchild == NULL) {//建立当前结点的后继线索
			pre->rchild = p;
			pre->rtag = 1;
		}
		pre = p;
		InThread(p->rchild, pre);//递归，右子树线索化
	}
}
void createInThread(TBTNode *root) {
	TBTNode *pre = NULL;//前驱结点指针
	if (root != NULL) {
		InThread(root, pre);
		pre->rchild = NULL;//非空二叉树，线索化
		pre->rtag = 1;//处理最后一个结点
	}
}
TBTNode *Frist(TBTNode *p) {
	while (p->ltag == 0)
		p = p->lchild;//最左下结点
	return p;
}
TBTNode *Next(TBTNode *p) {
	if (p->rtag == 0)
		return Frist(p->rchild);
	else
		return p->rchild;//rtag==1,直接返回后继线索
}
void Inorder(TBTNode *root) {
	for (TBTNode *p = Frist(root); p != NULL; p = Next(p))
		cout << p->data;
}

以上如有错误，请指出，大家共同学习进步。