剑指offer 36. 二叉搜索树与双向链表 

二叉搜索树的先序遍历序列是递增序列
设置pre指针来记录上一次访问结果

 1 /*
 2 // Definition for a Node.
 3 class Node {
 4 public:
 5     int val;
 6     Node* left;
 7     Node* right;
 8 
 9     Node() {}
10 
11     Node(int _val) {
12         val = _val;
13         left = NULL;
14         right = NULL;
15     }
16 
17     Node(int _val, Node* _left, Node* _right) {
18         val = _val;
19         left = _left;
20         right = _right;
21     }
22 };
23 */
24 class Solution {
25 private:
26     Node * pre ;
27     Node * head;
28     Node * last ;
29 
30 public:
31     Node* treeToDoublyList(Node* root) {
32         if(root ==NULL)
33             return NULL;
34         pre = NULL;
35         head = NULL;
36         last =NULL;
37         visit(root);
38         head->left = pre;
39         pre->right = head;
40         return head;
41 
42         
43     }
44     void visit(Node* root)
45     {
46         if(root == NULL)
47             return;
48         visit(root->left);
49         if(head == NULL)
50         {    
51             head = root;
52             pre = root;
53         }
54         else
55         {
56             pre->right = root;
57             root->left = pre;
58             pre = root;
59         }
60         visit(root->right);
61     }
62 };

 

posted @ 2022-01-12 21:49  BohrCh  阅读(29)  评论(0)    收藏  举报