LeetCode in Net
108. Convert Sorted Array to Binary Search Tree
Easy
Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.
A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.
Example 1:
Input: nums = [-10,-3,0,5,9]
Output: [0,-3,9,-10,null,5]
Explanation: [0,-10,5,null,-3,null,9] is also accepted: 
Example 2:
Input: nums = [1,3]
Output: [3,1]
Explanation: [1,3] and [3,1] are both a height-balanced BSTs.
Constraints:
1 <= nums.length <= 104-104 <= nums[i] <= 104numsis sorted in a strictly increasing order.
Solution
using LeetCodeNet.Com_github_leetcode;
/**
* Definition for a binary tree node.
* public class TreeNode {
* public int val;
* public TreeNode left;
* public TreeNode right;
* public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
public class Solution {
public TreeNode SortedArrayToBST(int[] nums) {
return MakeTree(nums, 0, nums.Length - 1);
}
private TreeNode MakeTree(int[] nums, int left, int right) {
if (left > right) {
return null;
}
int mid = (left + right) / 2;
TreeNode midNode = new TreeNode(nums[mid]);
midNode.left = MakeTree(nums, left, mid - 1);
midNode.right = MakeTree(nums, mid + 1, right);
return midNode;
}
}