24.二叉搜索树与双向链表

// 25.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"


struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};
class Solution {
public:
	TreeNode* Convert(TreeNode* pRoot)
	{
		if (pRoot == NULL) return NULL;

		TreeNode* ppLastNode = NULL;
		inOrder(pRoot, &ppLastNode);
		TreeNode* pRetHead = ppLastNode;
		while (pRetHead->left != NULL) {
			pRetHead = pRetHead->left;
		}
		return pRetHead;
	}

	void inOrder(TreeNode* pNode, TreeNode** ppLastNode) {
		if (pNode == NULL) return;

		if (pNode->left != NULL) {
			inOrder(pNode->left, ppLastNode);
		}

		// 关键代码
		pNode->left = *ppLastNode;
		if (*ppLastNode != NULL) {
			(*ppLastNode)->right = pNode;
		}
		*ppLastNode = pNode;

		if (pNode->right != NULL) {
			inOrder(pNode->right, ppLastNode);
		}
	}
};
int _tmain(int argc, _TCHAR* argv[])
{
	TreeNode root(10);

	TreeNode rootLeft(6);
	TreeNode rootRight(14);

	TreeNode rootLeftLeft(4);
	TreeNode rootLeftRight(8);

	TreeNode rootRightLeft(12);
	TreeNode rootRightRight(16);

	root.left = &rootLeft;
	root.right = &rootRight;
	rootLeft.left = &rootLeftLeft;
	rootLeft.right = &rootLeftRight;
	rootRight.left = &rootRightLeft;
	rootRight.right = &rootRightRight;
	Solution s;
	TreeNode* ret = s.Convert(&root);
	return 0;
}

	void inOrder(TreeNode* pNode, TreeNode** ppLastNode) {
		if (pNode == NULL) return;

		if (pNode->left != NULL) {
			inOrder(pNode->left, ppLastNode);
		}

		// 关键代码

		if (pNode->right != NULL) {
			inOrder(pNode->right, ppLastNode);
		}
	}

	void inOrder(TreeNode* pNode, TreeNode** ppLastNode) {
		if (pNode == NULL) return;

		if (pNode->left != NULL) {
			inOrder(pNode->left, ppLastNode);
		}

		// 关键代码
		pNode->left = *ppLastNode;
		if (*ppLastNode != NULL) {
			(*ppLastNode)->right = pNode;
		}
		*ppLastNode = pNode;

		if (pNode->right != NULL) {
			inOrder(pNode->right, ppLastNode);
		}
	}