【LeetCode】convert-sorted-list-to-binary-search-tree
程序员文章站
2022-03-09 08:02:36
...
题目描述:Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.
即将一个有序链表转换为一个平衡的二叉搜索树,即AVL树
思路:找到这个有序链表的中间结点,从而划分出左右两个部分,将中间结点作为根节点,从而分别建立出这个根结点的左右子树
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
/**
* Definition for binary tree
* struct TreeNode*root=NULL; {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode *sortedListToBST(ListNode *head) {
if(head==NULL)
return NULL;
if(head->next==NULL)
return new TreeNode(head->val);
ListNode *slow=head;
ListNode *fast=head->next->next;
while(fast && fast->next)
{
slow=slow->next;
fast=fast->next->next;
}
ListNode *l=head;
ListNode *m=slow->next;
ListNode *r=m->next;
slow->next=NULL;
TreeNode*root=new TreeNode(m->val);
root->left=sortedListToBST(l);
root->right=sortedListToBST(r);
return root;
}
};
上一篇: 二叉搜索树与双向链表
下一篇: 数据库||表约束