题目要求

思路
1.观察给的用例，本质上是把数据按照中序遍历连接起来
2.将结点以中序遍历的方式插入到数组中，注意这里是vector<TreeNode*>
3.将数组中的数据连接起来

代码实现

/*
struct TreeNode {int val;struct TreeNode *left;struct TreeNode *right;TreeNode(int x) :val(x), left(NULL), right(NULL) {}
};*/
class Solution {
public:vector<TreeNode*> res;TreeNode* Convert(TreeNode* pRootOfTree) {if (pRootOfTree == nullptr)return nullptr;midorder(pRootOfTree);for(int i = 0; i < res.size()-1; i++){res[i]->right = res[i+1];res[i+1]->left = res[i];}return res[0];}void midorder(TreeNode* pRootOfTree){if (pRootOfTree == nullptr)return;midorder(pRootOfTree->left);res.push_back(pRootOfTree);midorder(pRootOfTree->right);}
};