之前看过的前序遍历的线索二叉树感觉写的有点问题 这里更新一下我的思路

前序线索化

#include
using namespace std;

typedef int datatype;
typedef struct BitNode
{
	datatype Data;
	struct BitNode* leftchild;
	struct BitNode* rightchild;
	int lefttag;
	int righttag;
}Node;
#pragma region 前序线索化递归遍历
Node* previous = NULL;
void PreCuleOrder(Node* root)
{
	if (root == NULL)
	{
		return;
	}
	Node* tmpnode = NULL;
	tmpnode = root;
	if (tmpnode->leftchild == NULL )
	{
		tmpnode->leftchild = previous;
		tmpnode->lefttag = 1;
	}
	if (previous != NULL && previous->rightchild == NULL)
	{
		previous->rightchild = tmpnode;
		previous->righttag = 1;
	}
	previous = tmpnode;
	if (tmpnode->lefttag ==0)
	{
		PreCuleOrder(tmpnode->leftchild);
	}
	if (tmpnode->righttag == 0)
	{
		PreCuleOrder(tmpnode->rightchild);
	}
}
#pragma endregion

前序线索化遍历

#pragma region 前序遍历线索化二叉树
void PreIterativeTree(Node* root)
{
	if (root == NULL)
	{
		return;
	}
	Node* tmpnode = NULL;
	tmpnode = root;
	while (tmpnode!=NULL)
	{
		/*如果左子树一直非存在前继结点 那么一直遍历*/
		while (tmpnode->lefttag ==0)
		{	
			cout << tmpnode->Data << endl;
			tmpnode = tmpnode->leftchild;
		}
		/*出现连接上一层前继结点的叶子结点*/
		while (tmpnode->rightchild !=NULL)
		{
			if (tmpnode->lefttag ==0)
			{
				break;
			}
			else
			{
				cout << tmpnode->Data << endl;
				tmpnode = tmpnode->rightchild;
			}
		}
		if (tmpnode->rightchild == NULL)
		{
			cout << tmpnode->Data << endl;
			break;
		}
	}
}
#pragma endregion

主函数代码

int main(void)
{
	BitNode* n1 = new BitNode();
	BitNode* n2 =  new BitNode();
	BitNode* n3 =  new BitNode();
	BitNode* n4 =  new BitNode();
	BitNode* n5 =  new BitNode();
	BitNode* n6 =  new BitNode();
	BitNode* n7 =  new BitNode();
	BitNode* n8 =  new BitNode();
	BitNode* n9 =  new BitNode();
	n1->Data = 1, n2->Data = 2, n3->Data = 3, n4->Data = 4, n5->Data = 5, n6->Data = 6, n7->Data = 7, n8->Data = 8, n9->Data = 9;
	n1->leftchild = n2;
	n1->lefttag = 0;
	n2->leftchild = n4;
	n2->lefttag = 0;
	n4->leftchild = n5;
	n4->lefttag = 0;
	n1->rightchild = n3;
	n1->righttag = 0;
	n3->rightchild = n7;
	n3->righttag = 0;
	n3->leftchild = n6;
	n3->lefttag = 0;
	n7->leftchild = n9;
	n7->lefttag = 0;
	n7->rightchild = n8;
	n7->righttag = 0;
	PreCuleOrder(n1);
	PreIterativeTree(n1);
	return 0;
}

最终运行结果