题解 | #二叉搜索树与双向链表#

/*
struct TreeNode {
	int val;
	struct TreeNode *left;
	struct TreeNode *right;
	TreeNode(int x) :
			val(x), left(NULL), right(NULL) {
	}
};*/
class Solution {
public:	
	void midtrace(TreeNode* root){
		//
		if(root==nullptr) return;
		midtrace(root->left);
		if(savedPtr==nullptr) {
			Head=root;
			root->left=nullptr;
		}
		//非空情况下
		else{
			root->left=savedPtr;
			savedPtr->right=root;
		}
		savedPtr=root;
		midtrace(root->right);
	}
    TreeNode* Convert(TreeNode* pRootOfTree) {
        //中序遍历
		midtrace(pRootOfTree);
		return Head;
    }
	TreeNode* savedPtr=nullptr;
	TreeNode* Head=nullptr;
};