tsanmmmm2000's Tech Blog

Quesiton

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

My C# Solution

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode SortedArrayToBST(int[] nums) {
        if (nums == null) return null;
        return GetTreeNode(nums, 0, nums.Length - 1);
    }
    
    private TreeNode GetTreeNode(int[] nums, int low, int high)
    {
        TreeNode result = null;
        if (low <= high)
        {
            var mid = (low + high) / 2;
            result = new TreeNode(nums[mid]);
            result.left = GetTreeNode(nums, low, mid - 1);
            result.right = GetTreeNode(nums, mid + 1, high);            
        }
        return result;
    }
}