0108-convert-sorted-array-to-binary-search-tree.rb

# frozen_string_literal: true

# 108. Convert Sorted Array to Binary Search Tree
# https://leetcode.com/problems/convert-sorted-array-to-binary-search-tree
# Easy

=begin

Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.

### 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,null,3] and [3,1] are both height-balanced BSTs.

### Constraints:
* 1 <= nums.length <= 104
* -104 <= nums[i] <= 104
* nums is sorted in a strictly increasing order.

=end

# Definition for a binary tree node.
# class TreeNode
#     attr_accessor :val, :left, :right
#     def initialize(val = 0, left = nil, right = nil)
#         @val = val
#         @left = left
#         @right = right
#     end
# end
# @param {Integer[]} nums
# @return {TreeNode}
def sorted_array_to_bst(nums, l = 0, r = nums.size, m = (l + r) / 2)
  TreeNode.new(nums[m], sorted_array_to_bst(nums, l, m), sorted_array_to_bst(nums, m + 1, r)) if l < r
end