# Definition for a binary tree node.

class TreeNode

attr_accessor :val, :left, :right

def initialize(val)

@val = val

@left, @right = nil, nil

end

end

# @param {Integer[]} nums

# @return {TreeNode}

def sorted_array_to_bst(nums)

if nums.nil? or nums.size < 1

return nil

end

form_node nums, 0, nums.size - 1

end

def form_node(nums, left, right)

if left > right

return nil

end

if left == right

return TreeNode.new nums[left]

end

mid = left + Integer((right - left) / 2)

root = TreeNode.new nums[mid]

root.left = form_node nums, left, mid - 1

root.right = form_node nums, mid + 1, right

root

end

root = sorted_array_to_bst [1, 3]

puts root.val

puts root.right.val