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.

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Solution:

Tips:

recursion, tree

Java Code:

/** * 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 (null == nums || nums.length < 1) {            return null;        }                return sortedArrayToBST(nums, 0, nums.length - 1);    }        public TreeNode sortedArrayToBST(int[] nums, int begin, int end) {        if (begin > end) {            return null;        }        int mid = begin + (end - begin) / 2;        TreeNode node = new TreeNode(nums[mid]);        node.left = sortedArrayToBST(nums, begin, mid - 1);        node.right = sortedArrayToBST(nums, mid + 1, end);                return node;    }}