# LeetCode-109. Convert Sorted List to Binary Search Tree

## LeetCode-109. Convert Sorted List to Binary Search Tree

Posted by Jae on September 16, 2019

### 1、题目

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Example:

Given the sorted linked list: [-10,-3,0,5,9],

One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST:

0
/ \
-3   9
/   /
-10  5


### 3 实现

class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}

class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) { val = x; }
}

class Solution {
if (head == null) return null;

ListNode prev = new ListNode(0);
while (fast != null && fast.next != null){
fast = fast.next.next;
slow = slow.next;
prev = prev.next;
}
prev.next = null;
TreeNode root = new TreeNode(slow.val);
root.right = sortedListToBST(slow.next);

return root;
}
}


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