leetcode 897. 递增顺序查找树 c++

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897. 递增顺序查找树

分析

• 中序遍历
• 二叉树的构造

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
     TreeNode* increasingBST(TreeNode* root) {
       if(root==NULL){
           return root;
       }
       p=new TreeNode(-1);
       TreeNode* head=p;
       _increasingBST(root);
       return head->right;
    }
private:
    void _increasingBST(TreeNode* root){
        if(root->left!=NULL)
        {
          _increasingBST(root->left);   
        }
        
        p->left=NULL;
        TreeNode* t=new TreeNode(root->val);
        p->right=t;
        p=t;
        
        if(root->right!=NULL)
        {
          _increasingBST(root->right);   
        }
        return;
    }
private:
    TreeNode* p;
};