LeetCode OJ 108. Convert Sorted Array to Binary Search Tree

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

把一个有序的数组转换为一颗平衡二叉搜索树。每次找到中间节点作为根节点，根节点左边部分转换为左子树，右边部分转换为右子树。代码如下：

 /**

  * Definition for a binary tree node.

  * public class TreeNode {

  *     int val;

  *     TreeNode left;

  *     TreeNode right;

  *     TreeNode(int x) { val = x; }

  * }

  */

 public class Solution {

     public TreeNode sortedArrayToBST(int[] nums) {

         if(nums.length == 0) return null;

         return changeToBST(nums, 0, nums.length-1);

     }

     public TreeNode changeToBST(int[] nums, int left, int right){

         int mid = (right - left)/2 + left;

         TreeNode root = new TreeNode(nums[mid]);

         if(left==mid) root.left = null;

         else root.left = changeToBST(nums, left, mid-1);

         if(right==mid) root.right = null;

         else root.right = changeToBST(nums, mid+1, right);

         return root;

     }

 }

巴特西

LeetCode OJ 108. Convert Sorted Array to Binary Search Tree

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